SaaS User Acquisition: The London Founder's Ultimate Guide

So you’re a SaaS founder in London, and finding a firm to get you users feels like a nightmare. You’re being quoted eye-watering retainers by agencies in Shoreditch that talk a big game but show you case studies for cupcake shops. The truth is, most agencies don't get B2B SaaS, and even fewer understand how to acquire users without burning through your seed round in a month. But the problem isn't just the agencies, it's often the entire approach to advertising that's broken from the start.

Forget what you've been told. You don't need an agency that's 'specialised' in your exact vertical. You need a team of advertising experts who understand the mechanics of conversion, cost, and scale, regardless of the industry. This is a guide on how to actually think about user acquisition, what to demand from an agency, and how to build a system that brings in qualified leads without breaking the bank.

What if "industry expertise" is a myth?

Here’s the first hard truth: an agency that only works with, say, legal tech SaaS, isn’t necessarily better than one with broad B2B experience. In fact, they can be worse. They get complacent, recycle the same tired strategies for every client, and often lack the fresh perspective needed to crack a new market. What you should be looking for is a proven track record of getting results for businesses like yours – specifically, B2B and software.

When you're vetting an agency, ignore the sales pitch and go straight to their case studies. Are they showing you fluffy metrics like 'impressions' or 'reach'? Or are they showing you cold, hard numbers? Things like cost per trial, cost per user, and return on ad spend. For instance, I remember one B2B software client we worked on. They were struggling to get trials. We came in and built out a campaign on Meta Ads that brought in 5,082 software trials at just $7 a pop. For another SaaS client, this time on Google Ads, we drove 3,543 new users at a cost of only £0.96 each. That’s the kind of evidence you want to see. It’s not about them knowing the ins and outs of your specific software; it’s about them knowing the ins and outs of the ad platforms.

A good team can take the principles that worked for a medical job matching SaaS (we took their cost per user from £100 down to £7) and apply them to an environmental controls company (we cut their cost per lead by 84%). The platform mechanics and audience psychology are surprisingly similar. The goal is to find someone who understands how to turn clicks into customers, not someone who can recite the history of your niche.

How do I spot a good agency from a bad one then?

Alright, so if specific niche experience isn't the be-all and end-all, what should you actually look for? It comes down to two things: their proof and their process.

First, look for detailed case studies that show relevant results for businesses like yours. B2B, software, lead generation, user acquisition. Don't be afraid to ask questions. How long did it take to get those results? What was the ad spend? What platforms did they use? If their case studies are all B2C ecommerce, they're probably not the right fit for your SaaS business, no matter how impressive the numbers are.

Second, get on a call with them. And I don’t mean a sales call where a junior account exec reads from a script. You want to talk to a strategist, an expert. The best agencies will offer some form of free, initial consultation where they actually look at your business and give you real advice. We do this all the time. A prospective client comes to us, we’ll spend time looking at their ad accounts, their landing pages, their offer, and give them a mini-strategy right there on the call. It gives them a taste of the expertise they'd be getting. If an agency is cagey, won't give you any ideas upfront, or just promises you the world without any substance, walk away. They should be able to identify your main challenges and propose a logical plan of attack within the first conversation.

A final point on this. Be wary of asking for references. Tbh, if a potential client has seen our detailed case studies, had a free strategy session with us, and still asks to speak to one of our current clients, it’s a massive red flag. It signals a fundamental lack of trust from the outset, and that's not a foundation for a good partnership. A strong portfolio of results should speak for itself.

Why are my leads so expensive? Calculating what you can *really* afford

Every London founder I speak to says the same thing: "My cost per lead is too high." They're obsessed with getting it as low as possible. This is the wrong question. The right question is, "How high a Cost per Acquisition (CPA) can I afford to acquire a great customer?" The answer is tied to your Customer Lifetime Value (LTV).

Most SaaS founders don't have a proper grasp on this number, so they operate in the dark, terrified of spending money. Let's fix that right now. This is the maths that separates the businesses that scale from those that stagnate.

Here’s the simple calculation:

LTV = (Average Revenue Per Account (ARPA) * Gross Margin %) / Monthly Churn Rate

Let's plug in some numbers for a hypothetical London FinTech SaaS:

• -> ARPA: £300/month
• -> Gross Margin: 85% (pretty typical for software)
• -> Monthly Churn Rate: 5%

LTV = (£300 * 0.85) / 0.05
LTV = £255 / 0.05
LTV = £5,100

So, each customer you sign up is worth £5,100 in gross margin over their lifetime. A healthy LTV to Customer Acquisition Cost (CAC) ratio is at least 3:1. This means you can afford to spend up to £1,700 (£5,100 / 3) to acquire a single new customer.

Suddenly that £50 lead from Google Ads or that £200 demo booked from LinkedIn doesn't seem so expensive, does it? It looks like a bargain. This single calculation frees you from the tyranny of cheap, low-quality leads and gives you the confidance to invest in channels that attract high-value customers. You can't win in a competitive market like London by being cheap; you win by being smart and knowing your numbers better than anyone else.

Here's a simple table to see how this plays out:

Your customer isn't a demographic, they're a person with a problem

Okay, so you know what you can afford to spend. Now, who are you spending it on? Most agencies will ask for your Ideal Customer Profile (ICP), and you'll give them something useless like "SaaS companies in the UK with 10-50 employees." This is why your ads fail. It’s generic, it’s lazy, and it leads to messaging that speaks to no one.

Your ICP is not a demographic. It's a problem state. It's a nightmare. Your customer is the Head of Sales at a mid-size tech company in the Silicon Roundabout who is terrified of missing their quarterly target because their team is wasting hours on manual data entry. Your customer is the founder of a creative agency in Soho who can't sleep because they have no idea what their cash flow looks like next month.

You need to get incredibly specific about this pain. What are the exact words they use to describe it? What are the consequences of not solving it? (e.g., losing their best staff, getting beaten by a competitor, failing to secure the next funding round). Once you understand the nightmare, you can craft a message that feels like you're reading their mind.

Then, you find them where they live online. It’s not about blasting ads everywhere. It's about precision. What newsletters do they actually read on their commute on the tube? (Probably not the generic tech news). What podcasts do they listen to? What specific SaaS tools do they already pay for? Are they in niche Slack communities? Are they following certain influencers on LinkedIn? This is the real targeting intelligence. Do this work first, or you have no business spending a single pound on ads.

What's the right platform for a London SaaS?

Once you know who you're targeting and what pain you're solving, you can pick the right battlefield. For a B2B SaaS business, you really only have three viable options for paid acquisition.

1. Google Search Ads: The Low-Hanging Fruit
This is for capturing intent. These are people who are already problem-aware and actively looking for a solution. They're typing things like "best crm for small business uk" or "ai implementation agency london" into Google. Your job is to be the top result. This is often the most effective channel to start with because the leads are highly qualified. They have a need *right now*. A campaign we ran for a software company using Google Ads, as I mentioned earlier, brought in users for just £0.96 each because we targeted the right, high-intent keywords.

2. LinkedIn Ads: The Sniper Rifle
LinkedIn is expensive, but it's powerful for its targeting. This is where you go when you need to reach a specific person in a specific company. Want to target CTOs at FTSE 250 companies in the financial services sector? You can do that. It's brilliant for high-ticket offers where the deal size justifies the higher lead cost. We've seen CPLs for B2B decision-makers at around $22, which is a great price when the LTV is in the thousands. The key here is a hyper-relevant offer. Don't just send them to your homepage; send them to a case study or a whitepaper that speaks directly to their role and industry.

3. Meta (Facebook/Instagram) Ads: The Scaling Engine
Most people think of Meta as a B2C platform, but they're dead wrong. It can be an incredibly powerful B2B tool, especially for lower-priced SaaS or when you need to scale. Why? Lookalike audiences. Once you have a list of your best customers, you can ask Meta to find millions of other people just like them. It's shockingly effective. We ran a campaign for a B2B software that drove 4,622 registrations at just $2.38 each. Another one got 1,535 trials. You cant get that kind of volume and cost-efficiency on LinkedIn. You start with broader interest targeting (e.g., people who like 'Shopify' and are 'business page admins') to gather data, then you unleash the lookalikes to scale.

The right strategy is often a mix. Use Google to capture active demand, LinkedIn for high-value targets, and Meta to build audiences and scale what's working. Don't let an agency tell you to just stick to one platform because it's all they know.

The "Request a Demo" button is where your leads go to die

This might be the most important part of this whole guide. The most common failure point in B2B advertising has nothing to do with the ads themselves. It's the offer. The "Request a Demo" button is arrogant. It presumes your prospect, a busy London professional, has nothing better to do than schedule a meeting to be sold to. It's high friction and low value.

Your offer's only job is to deliver a moment of undeniable value. An "aha!" moment that makes the prospect sell themselves on your solution. For a SaaS founder, you have an unfair advantage here: your product.

The gold standard offer is a completly free trial (no credit card) or a generous freemium plan. Let them use the actual product. Let them experience the transformation for themselves. When the product proves its own value, the sale becomes a formality. This is exactly how you get 5,082 trials, as I talked about earlier, like our client did. You make it incredibly easy and valuable for someone to say yes.

If for some reason you can't offer a free trial, you must create a substitute. Bottle up your expertise into a tool or asset that solves a small, real problem for free.

• -> For a data analytics SaaS: A free 'Data Health Check' that finds the top 3 errors in their database.
• -> For a security SaaS: A free scan that identifies the most common vulnerabilities on their website.
• -> For us, as an agency: A free 20-minute strategy session where we audit their failing ad campaigns.

You must give value to get value. Delete the demo button and replace it with something that actually helps your prospect. Your conversion rates will thank you for it.

Your Roadmap to Cost-Effective User Acquisition

So, let's pull all this together. Acquiring users for your SaaS in a competitive market like London is more than possible; it just requires a smarter approach. It's about moving from a mindset of 'cost' to one of 'investment', armed with the right numbers and a relentless focus on solving a real customer problem.

I've detailed my main recommendations for you below. This isn't a magic bullet, but it's the strategic framework we've used to help countless SaaS businesses, from pre-seed startups to established players, scale their user base profitably. It's about being methodical, data-driven, and never forgetting that you're talking to a person, not a persona.

Navigating this landscape alone is tough. While this guide provides the blueprint, the execution requires constant testing, optimisation, and deep platform expertise. It's a full-time job. That's where having an experienced partner can make all the difference, helping you avoid costly mistakes and accelerate your path to predictable, profitable growth.

If you're a SaaS founder in London and you'd like an expert, no-strings-attached opinion on your current user acquisition strategy, we offer a free 20-minute consultation. We'll review your campaigns, your offer, and your funnel, and give you honest, actionable advice you can implement immediately.