The UK Founder's Playbook for Vetting and Hiring Paid Media Agencies & Consultants

Hiring a paid media agency or consultant in the UK is, frankly, a minefield. The market's flooded with cowboys who've watched a few YouTube videos and now call themselves experts. They'll promise you the earth, show you some flashy slides full of vanity metrics, and then burn through your cash with very little to show for it. I've seen the inside of dozens of ad accounts after these so-called 'agencies' have had their way with them, and it's rarely a pretty sight.

Most founders make the same critical mistake right at the start. They focus on the wrong question. They ask, "How much do you charge?" instead of asking, "How much can I afford to pay to acquire a customer?" The answer to the second question is the only thing that actually matters, and it has nothing to do with the agency's price list and everything to do with your own business's economics. This is the playbook for vetting and hiring an expert in the UK, based on what actually drives profit, not what sounds good in a pitch deck.

First off, why are you even thinking of hiring someone?

Before you even start looking, you need to be brutally honest with yourself. Are you hiring someone because you're genuinely ready to scale with a proven offer, or are you hoping an agency can magically fix a product that nobody wants to buy? No amount of clever advertising can fix a broken offer. As I've seen time and time again, the number one reason campaigns fail is the offer itself. It either isn't valuable enough or there's no real demand for it. If your offer isn't converting with the traffic you already have, you need to fix that first.

But let's assume your offer is solid. You're making sales, you have happy customers, but you've hit a wall. You're either too busy running the business to manage ads properly, or you've realised that clicking 'Boost Post' isn't a real strategy. This is the right time to consider hiring help. You're not buying ads; you're buying speed and expertise. You're paying to avoid the "learning tax"—that period of months, or even years, where you'd be burning your own money trying to figure out what an expert already knows. Deciding between doing it yourself or hiring a UK agency is about weighing that learning tax against the cost of their retainer.

The one metric that changes everything: Customer Lifetime Value (LTV)

Right, forget everything you think you know about budgeting for ads. Forget industry benchmarks for cost-per-click. It's all noise. The only number that should guide your decision is your Customer Lifetime Value (LTV). LTV tells you how much gross margin a typical customer will generate for your business over their entire relationship with you. Once you know this, you know how much you can afford to spend to acquire them, which is your Customer Acquisition Cost (CAC).

The maths is actually pretty simple. You need three numbers:

• Average Revenue Per Account (ARPA): How much a customer pays you on average, per month.
• Gross Margin %: Your profit margin on that revenue after accounting for costs of goods sold.
• Monthly Churn Rate %: The percentage of customers you lose each month.

The calculation is: LTV = (ARPA * Gross Margin %) / Monthly Churn Rate

A healthy business model aims for an LTV:CAC ratio of at least 3:1. This means if your LTV is £9,000, you can afford to spend up to £3,000 to acquire that customer. This single peice of information completely reframes your conversations with potential agencies. The question is no longer "What's your monthly fee?" but "Can you acquire customers for under £3,000?" Suddenly, a £2,500 per month agency fee doesn't seem so expensive if they can deliver even just two or three high-value customers.

To make this real, I've built a calculator for you. Play around with your own numbers. This is the foundation of a profitable ad strategy.

How to actually vet an agency (and see through the nonsense)

Armed with your LTV and target CAC, you're ready to start talking to people. This is where you need a process to filter out the time-wasters. Finding the right UK paid ads consultant is about asking the right questions and knowing what a good answer looks like.

Step 1: The Case Study Interrogation

Every agency website has a 'Case Studies' page. Most of it is fluff. Your job is to dig deeper. Don't be impressed by big logos or flashy revenue numbers without context.

• Relevance is everything. If you're a B2B SaaS company in the UK, a case study about a US-based eCommerce brand selling women's apparel is almost useless to you. The audiences, platforms, and strategies are completely different. You need to see evidence they've got results for businesses like yours. I remember one client, a medical job matching SaaS, was impressed by an agency's eCommerce results. We came in and took their CPA from £100 down to £7 because we understood the nuances of SaaS advertising on Google and Meta, which the other agency didn't.
• Demand real metrics. "10 Million Views" for a luxury brand sounds great, but it's a vanity metric. It tells you nothing about the business impact. You want to see the numbers that matter: Cost Per Lead (CPL), Cost Per Acquisition (CPA), Return On Ad Spend (ROAS). For a B2B software client on LinkedIn, we got the CPL down to $22 for highly qualified decision makers. That's a meaningful number.
• Question the results. A "1000% Return On Ad Spend" for a subscription box sounds amazing, but what was the ad spend? £100? What was the customer churn rate? If the numbers look too good to be true, they probably are. Ask them to walk you through the strategy that achieved it. If they can't explain it clearly, that's a red flag.

To help, here’s a simple flowchart for how you should be thinking about their past work.

Step 2: The Discovery Call Test

The first call is your interview. You're the one hiring. Don't let them just run through a standard sales pitch. Your goal is to gauge their actual expertise and how they think. Many UK founders feel they are clueless when hiring an agency, but asking these questions will quickly separate the experts from the amateurs.

Here's what you should be asking:

• "Based on what you've seen of our business, what's the first thing you would test?" A bad answer is generic, like "We'd test new creatives." A good answer is specific: "Your current offer is a 'Request a Demo' button. That's high friction. We'd first test an offer for a free, automated audit tool or a valuable case study download to lower the barrier to entry and capture more leads."
• "What's your process for creative and copywriting?" Many agencies expect you to provide all the assets. This is a huge hidden workload for you. A proper agency has in-house or trusted freelance copywriters and designers who understand direct response principles.
• "We've calculated our LTV to be £X and our target CAC is £Y. How does that affect your proposed strategy?" This is the killer question. If they look at you with a blank expression or try to dodge the question, the call is over. An expert will lean in. They'll say, "That's great. Knowing we can spend up to £Y gives us a lot more room to test audiences on platforms like LinkedIn, which are more expensive but deliver higher quality leads." This shows they think about your business, not just their tactics.
• "What do you think of our current offer?" A great consultant isn't afraid to tell you your baby is ugly. They should challenge your assumptions. They might say, "You're selling an accounting system to B2B clients without a free trial. That's going to make any ad campaign incredibly difficult because the trust barrier is too high." This is the kind of honest feedback that's actually valuable.

Step 3: The "Free Audit" Litmus Test

Many agencies, including us, offer a free initial consultation or account audit. Don't view this as them doing you a favour. View it as your final exam for them. Their performance here tells you everything you need to know about what it would be like to work with them.

A bad audit is a generic, templated PowerPoint presentation that talks about "best practices" without ever looking at your specific situation. It's a veiled sales pitch designed to get you to sign a contract.

A good audit is a proper working session. They'll ask for read-only access to your ad accounts (a serious agency will do this). They'll come to the call having already identified specific problems and opportunities. They'll say things like:

"I can see you're running one big retargeting audience. We should split that out. People who abandoned a cart are much more valuable than people who just visited the homepage. We can create a separate, more agressive campaign for them."

"Your Google Search campaigns are targeting broad keywords which is bringing in a lot of irrelevant traffic. We'd introduce more specific 'long-tail' keywords and negative keywords to pre-qualify your clicks and stop wasting money."

They should give you at least one or two actionable peices of advice that you could go and implement yourself immediately. They are demonstrating their value, not just talking about it. This is the single biggest indicator of a true expert.

What are UK agency fees and what should I expect to pay?

Agency pricing models in the UK can be confusing. Once you've vetted an agency for expertise, you then need to understand how they charge. The fee itself is less important than the value delivered, but you still need to know what you're getting into. The conversation about London ad agency fees can be particularly tricky given the higher overheads.

Here are the most common models:

For most founders in the UK starting out, a flat monthly retainer is the most transparent and sensible model. It allows the agency to focus on getting the foundations right without being pressured to simply increase your budget. The question of whether UK Facebook Ads management costs are justified comes back to your LTV. If a £2,000 retainer brings in customers worth £10,000 each, it's an incredible investment.

Red Flags: When to Walk Away Immediately

During your vetting process, certain things should set alarm bells ringing. If you encounter any of these, it's usually best to politely end the conversation and move on.

• "We guarantee results." This is the biggest lie in advertising. No one can guarantee results. There are far too many variables (your offer, your website, seasonality, competition, the platforms themselves). An expert talks about a methodical process of testing and optimisation, not guarantees.
• They focus on vanity metrics. If their pitch is all about clicks, impressions, and reach, they don't understand business. You care about leads, sales, and profit. A good partner speaks your language.
• Long, inflexible contracts. A 12-month lock-in from day one is a massive red flag. A confident agency will often start with a 3-month initial term and then move to a 30-day rolling contract. They know they need to keep delivering value to keep your business.
• Lack of transparency. You should always have full ownership and admin access to your ad accounts. The data is yours. Any agency that sets up accounts in their own name and doesn't give you access is hiding something.
• They can't explain the 'why'. If you ask why they're suggesting a particular strategy and they just say "it's best practice," that's not good enough. An expert can explain the logic behind their recommendations in a way that makes sense to you.
• Asking for references too early. This one is a bit contrarian, but it's from experience. If you've seen their detailed case studies, had a deep strategy session where they provided real value, and you still don't trust them enough to proceed... you probably never will. Tbh if someone asks us for references after all that, it signals a lack of trust that means we're probably not a good fit for each other.

Making The Final Decision

Choosing an agency or consultant is a significant decision. You're not just hiring a supplier; you're bringing on a growth partner. The right one will feel like an extension of your own team. They will be obsessed with your numbers, challenge your assumptions, and be proactive in finding new opportunities to grow your business.

Don't rush the process. It's better to spend an extra month finding the right partner than to jump in with the wrong one and waste six months and thousands of pounds. Use your LTV as your north star, interrogate their case studies, test their expertise on the discovery call, and trust your gut. For London-based B2B firms, the choice between an agency or a freelancer can be even more complex, but the vetting principles remain the same.

If this all still feels overwhelming, or you just want a second pair of expert eyes on what you're currently doing, the best way forward is to experience the expertise first-hand. A good audit can provide more clarity in 30 minutes than weeks of research. That's why we offer a completely free, no-obligation strategy session where we'll go through your ad account with you live, and give you actionable advice you can use, whether you decide to work with us or not. It's our way of proving our value, not just talking about it.