The verdict in three sentences
A precise project brief (RFP) is the single best lever against nasty surprises: scoped projects in London show 30 % fewer overruns than those launched on a verbal brief. A B2B marketing website of 12 to 18 pages sits in 2026 between GBP 6,000 and 15,000, delivered in 6 to 9 weeks. Without written acceptance criteria and penalties, you can neither compare quotes nor hold a vendor accountable.
What the brief must contain
A good brief runs 10 to 15 pages and answers one question: can a vendor who doesn't know you price it without coming back five times? Structure it in numbered blocks so agencies can respond point by point.
| Brief section | What it specifies | Impact on the quote |
|---|---|---|
| Context & goals | Market, B2B targets, KPIs (leads, meetings) | Frames the scope |
| Sitemap | Exact page list (12-18) | Real chiffrage |
| Content | Who writes, who supplies visuals | +GBP 1,500-4,000 if agency-owned |
| Features | Forms, multilingual, blog, CRM | Most variable line |
| Design | Existing brand or new UI | +GBP 2,000-5,000 if new UI |
| Technical | CMS, hosting, GDPR, performance | Drives the retainer |
| Acceptance & penalties | Sign-off criteria, deadlines | Protects the budget |
| Timeline & budget | Milestones, indicative range | Filters candidates |
Always state whether copywriting and translation are yours or the agency's responsibility: it's the number-one source of variance between London quotes.
Reference budgets and timelines 2026
The ranges below reflect the London agency and studio market in 2026 (order of magnitude, excluding SEO and campaigns).
| B2B site profile | Pages | Budget GBP | Timeline |
|---|---|---|---|
| Essential brochure | 8-12 | 4,500 - 7,000 | 5-7 weeks |
| Standard B2B site | 12-18 | 7,000 - 12,000 | 6-9 weeks |
| Premium + blog + EN/FR | 18-25 | 12,000 - 18,000 | 9-12 weeks |
| Rebuild with content migration | 15-30 | 10,000 - 20,000 | 10-14 weeks |
Add a 10-15 % contingency for post-acceptance tweaks and budget an annual retainer (see dedicated article) inside the brief: treat it as a selection criterion, not an option to negotiate later.
Vendor scoring grid
The brief should include the grid you'll judge responses on. Sharing it with candidates raises the quality of the quotes you receive.
| Criterion | Weight | What you check |
|---|---|---|
| Price (normalised scope) | 40 % | Same scope for all |
| Comparable B2B references | 25 % | Concrete cases, results |
| Timeline & method | 15 % | Realistic schedule |
| Retainer & warranty | 20 % | SLA, fixes included |
Mini case study
Need a professional website?
Kolonell builds websites that attract clients, optimized for the Sénégalese market. Free quote in 2 minutes.
Sophie, head of marketing at an industrial SME in London (45 staff), starts a rebuild with no brief. First quotes: GBP 5,800, 11,200 and 16,500, uncomparable. She writes a 12-page brief in 2 days (about GBP 900 of internal time). The new quotes, on a normalised scope, land between GBP 9,000 and 11,500. By clarifying that content will be produced in-house, she saves roughly GBP 3,200 and avoids two change orders estimated at GBP 2,500. Brief ROI: over 5x the time invested.
FAQ
How long does it take to write a brief?
Budget 2 to 4 days of internal work for a 12-18 page B2B site. It's the best investment of the project: it drives comparable quotes and cuts overruns by 30 %.
Do I need a brief for a GBP 6,000 site?
Yes, even a short one. A 6-8 page brief is enough for a GBP 6,000 project and prevents the page, content and deadline misunderstandings that inflate the bill.
Who writes the content, us or the agency?
Spell it out: copy and translation can represent GBP 1,500-4,000. If you supply the text, require the quote to state it explicitly.
Can I include late-delivery penalties?
Yes. A clause of 0.5 to 1 % of the value per week of delay, capped at 10 %, is common in 2026 and readily accepted by serious agencies.
Is the brief legally binding?
Annexed to the contract it becomes contractual and serves as the acceptance reference. Anything not in it is out of scope and billable as a change order.
Let's scope your project. Send us your target sitemap, indicative budget and preferred launch date: we'll return a tender-ready brief and a quote on a normalised scope. Detailed quote within 48 h. WhatsApp +221 77 596 93 33.
Mohamed Bah
Fondateur, Kolonell
Passionate about digital and entrepreneurship in Africa, Mohamed has been helping Sénégalese businesses with their digital transformation since 2020. Founder of Kolonell, he believes every SME deserves a professional and accessible online présence.
