SaaS Marketing: Consultant or Agency in London?

You’re a SaaS founder in London. You've built something you believe in, maybe you've got some early traction from your network, but now you’re staring at the massive challenge of user acquisition. You know paid advertising is probably the answer to predictable growth, but the landscape is a minefield. The big question looms: do you hire a SaaS marketing consultant, or do you go all-in with a full-service agency?

Tbh, most founders frame this question completely wrong. They see it as a choice between two types of service providers. It's not. It's a question of what your business needs *at this exact moment*. Getting this wrong is the fastest way to burn through your seed round with very little to show for it. I've seen it happen dozens of times. A promising SaaS in Shoreditch hires a big-name agency, gets assigned a junior account manager who doesn't understand churn, and six months later they've spent £50,000 on vanity metrics and have zero PQLs (Product Qualified Leads).

The choice isn't just about budget; it's about matching the right kind of expertise to your specific stage of growth and the problems you're facing. This guide is built to give you a clear framework for making that decision, based on my experience running paid ad campaigns for B2B SaaS companies, including some right here in the UK. We'll cut through the sales pitches and get to the core of what will actually help you grow. For a comprehensive overview of how to get started, you might want to look at the London founder's playbook for paid advertising.

So, what does a paid ads consultant actually do?

Let's get one thing straight. A genuine paid ads consultant is not just a freelancer who runs your campaigns for you. If that's what they're offering, they're a one-person agency, not a consultant. There's a huge difference.

A consultant is a strategist. An architect. Their job is to diagnose the deep, underlying issues in your growth model and design the blueprint for a scalable customer acquisition machine. They don't just ask about your ad budget; they ask about your churn rate, your LTV, your sales cycle, and your product onboarding. Their primary deliverable isn't a weekly report on click-through rates; it's a strategic plan.

Think of it like this: you wouldn't hire a construction company and say "build me a house". You'd hire an architect first to understand your needs, survey the land, and draw up detailed blueprints. The consultant is your architect. They should be helping you with:

• -> Unit Economics Modelling: Before you spend a single pound on ads, you need to know your numbers. What's your true Customer Lifetime Value (LTV)? Based on that, what is the absolute maximum you can afford for your Customer Acquisition Cost (CAC)? A good consultant will help you build this model from the ground up. Without it, you're flying blind.
• -> Ideal Customer Profile (ICP) Definition: I'm not talking about "companies with 50-200 employees". I mean getting deep into the psychographics. What's the career-threatening nightmare that keeps your ICP awake at night? What podcasts do they listen to? A consultant helps you define this "problem state" so your messaging actually resonates.
• -> Strategic Channel Selection: Should you be on LinkedIn, Google Search, Meta? A consultant’s job isn't to say "yes to all" but to identify the one or two channels with the highest leverage for your specific ICP and offer, and map out a plan to dominate them.
• -> The Offer & Funnel: Most B2B ads fail not because of the targeting, but because of the offer. "Request a Demo" is an arrogant, high-friction call to action. A consultant will help you design a low-friction, high-value offer (like a free tool, an audit, or a true product-led trial) that actually gets high-quality prospects into your ecosystem.
• -> Measurement Framework: They'll help you set up proper tracking to measure what actually matters—PQLs, demo-to-close rate, and ultimately, ROAS—not just top-of-funnel fluff.

In short, you hire a consultant when you have a "how" or "why" problem. "How do we build a scalable acquisition model?" or "Why are our current ads not converting?". They provide the strategy. Finding the right person can be tough, but this UK guide to hiring a paid ads consultant is a solid place to start.

And what about a paid ads agency?

If the consultant is the architect, the agency is the construction company. They are the execution team. A good agency has a team of specialists—strategists, copywriters, designers, ad managers, data analysts—and established processes to implement a marketing plan at scale.

You hire an agency when you have a solid, validated blueprint and you need the manpower and systems to build the house. Their role is to take a proven strategy and execute it flawlessly, day in and day out. This includes:

• -> Campaign Management: The daily nuts and bolts of building, launching, and monitoring campaigns across multiple platforms.
• -> Creative Production: Designing the ad visuals, writing the copy, and producing video assets. A good agency will have in-house resources or trusted partners for this.
• -> A/B Testing and Optimisation: Systematically testing different audiences, creatives, and landing pages to continuously improve performance and drive down CAC.
• -> Reporting and Analysis: Compiling the data and providing regular reports on performance against KPIs.
• -> Scaling: Once you find a winning formula, an agency has the resources and experience to carefully increase the budget without breaking the unit economics.

The danger is hiring the agency *before* you have the blueprint. When a SaaS founder with an unvalidated offer and unclear ICP goes to an agency, the agency is forced to guess. They'll throw a bunch of stuff at the wall to see what sticks, and you'll be paying for their education. This is where budgets get incinerated. An agency is at its most powerful when you can hand them a clear plan and say, "Go build this." The decision isn't just between DIY and an agency, but understanding when to bring in professional help, a topic covered well in this guide on DIY vs Agency management.

Your London SaaS Decision Framework: Consultant or Agency?

Alright, so how do you choose? It comes down to an honest assessment of three things: your stage, your resources, and your problem. There's no one-size-fits-all answer, but we can get pretty close with a simple decision tree. Ask yourself these questions in order.

The Crucial First Step: Know Your Numbers

Before you even think about hiring anyone, you absolutely must have a handle on your unit economics. The most common reason SaaS founders fail with paid ads is that they don't know how much they can afford to spend to acquire a customer. You can't delegate this understanding. I remember one campaign for a medical job matching SaaS where we took their cost per user acquisition from £100 down to just £7. This was only possible because we first understood the LTV of their users, which gave us the room to test and find a profitable acquisition channel.

This is where LTV comes in. It's the total profit you expect to make from an average customer over the entire time they stay with you. Once you know your LTV, you can determine a target Customer Acquisition Cost (CAC) that will keep your business healthy (a common benchmark is an LTV:CAC ratio of 3:1 or higher).

To help you with this, here's a simple calculator to estimate your LTV. Play around with the numbers and see how small changes in churn or revenue can dramatically affect what you can afford to spend on marketing.

How to Spot a Bad Fit: Red Flags for London Founders

The London market is crowded. There are hundreds of agencies and consultants, and frankly, a lot of them are not equipped to handle the specific challenges of B2B SaaS. Whether you're talking to a consultant or an agency, you need to be ruthless in your vetting process. Here are some of the biggest red flags I've seen.

Agency Red Flags:

• -> The Bait and Switch: You have a great sales call with a senior strategist who really seems to get your business. You sign the contract, and on the kickoff call, you're introduced to your new day-to-day contact: a 23-year-old account manager with six months of experience. This is incredibly common. Insist on knowing exactly who will be working on your account before you sign anything.
• -> Vague Promises & Focus on Vanity Metrics: If their pitch is full of promises about "brand awareness," "reach," and "engagement," run away. You're a SaaS business. You need users, trials, and demos that turn into paying customers. Ask them specifically about their experience driving PQLs and reducing CAC for other SaaS clients. If they can't show you a case study, like one campaign where we drove 5,082 software trials for a client on Meta Ads, they're not the right fit. For more on what to look for, check out this guide on vetting paid ads agencies in London.
• -> A "Secret Sauce" or "Proprietary Platform": There are no secrets in paid ads. There are just strategy, process, data, and execution. If an agency claims to have a "proprietary AI" or a secret method they can't explain, it's almost always nonsense designed to lock you in and obscure what they're actually doing.

Consultant Red Flags:

• -> All Theory, No Practice: A consultant who hasn't actively managed campaigns recently can be out of touch. The platforms change constantly. Ask them when they last ran a campaign themselves. Their advice needs to be grounded in current, real-world experience, not what worked two years ago.
• -> No Customisation: If they present you with a generic, one-size-fits-all "growth hacking" plan in the first call without deeply digging into your business, your customers, and your data, they're a theorist, not a strategist. A good consultant's first step is always diagnosis.
• -> Unwillingness to Get Their Hands Dirty: While a consultant's main job is strategy, the best ones aren't afraid to jump into your ad account or analytics to find the real insights. If they only want to provide high-level advice from a distance, their impact will be limited. It's a tricky balance, and the difference between hiring an agency vs a freelancer or consultant often comes down to this level of involvement.

The Hybrid Approach: The Best of Both Worlds?

For many SaaS companies, especially those in the post-PMF, early scaling phase, the choice isn't a strict binary. A powerful and often more cost-effective model is the hybrid approach.

This is where you hire an experienced consultant on a fractional or project basis to act as your strategic lead. They do the heavy lifting on strategy, modelling, and planning. Then, you hire a smaller, more execution-focused agency or even a skilled freelancer to implement that plan under the consultant's guidance.

This model gives you several advantages:

1. Senior Strategy: You get the benefit of a top-tier strategist's brain without the massive overhead of a big agency's senior team.
2. Cost-Effective Execution: You can use more affordable resources for the day-to-day management, since the core strategy is already defined.
3. Accountability: The consultant acts as your internal expert, able to hold the execution team accountable to the right metrics and ensure the strategy is being implemented correctly.
4. Flexibility: It’s much easier to scale up or down with a freelancer or small agency, and you’re not locked into a long-term, high-cost retainer.

This does require more management from you, the founder, as you'll be coordinating two seperate parties. But for those willing to put in the effort, it can provide a level of expertise and value that's hard to beat. It's about finding the right experts for the right job, which is a common theme when looking for B2B SaaS ads experts in the UK.

How Much Should This Cost in London? A Realistic Look at Fees

Let's talk money. Pricing in London is, unsurprisingly, at a premium. Here’s a realistic breakdown of what you can expect to pay for quality help. Anything significantly cheaper should be viewed with suspicion—you tend to get what you pay for.

Consultants: They typically work on a day rate or a fixed project fee. For a senior SaaS consultant in London, expect to pay anywhere from £700 to £1,500+ per day. A typical strategic project (e.g., building a 3-month growth plan) might take 4-8 days, costing between £2,800 and £12,000.

Agencies: Most work on a monthly retainer. For a specialist B2B or SaaS agency in London, retainers will likely start at £2,500 - £4,000 per month and go up significantly from there. This fee is usually just for management and doesn't include your ad spend. Some also charge a percentage of ad spend (e.g., 15-20%), but this is more common for very large accounts. Understanding the nuances of these costs is vital, and you can get a more detailed breakdown in this complete guide to London ad agency fees.

The key isn't just the price tag, but the value. A £5,000 project with a consultant that unlocks a scalable acquisition channel and prevents you from wasting £50,000 with the wrong agency is an incredible bargain. Conversely, a cheap £1,500/month agency that just burns through your ad spend with no results is a massive financial drain. Don't optimise for cost; optimise for expertise.

My Final Recommendations for London SaaS Founders

So, we've covered a lot of ground. The arguement of consultant vs. agency is nuanced, and the right path is completly dependant on your specific situation. To make it as actionable as possible, I've summarised my main advice below.

Ultimately, the decision rests on a clear-eyed assessment of your business. Don't let a slick agency sales deck or a consultant's impressive CV sway you. Diagnose your own needs first. Are you struggling with strategy or with execution? The answer to that question will point you to the right partner who can genuinely help you acheive your growth objectives.

Navigating this is tough, especially when you're also trying to build a product and a team. If you're a SaaS founder in London and you're still unsure which path is right for you, or you just want a second opinion on your current paid advertising efforts, we offer a free, no-obligation 20-minute strategy session. We can take a look at your business, your goals, and help you build a clear plan of action.

Hope that helps!