Why Write a Business Plan at All?
Business plans have a reputation for being something you write once, file away, and never look at again. That reputation is partly deserved — but it's usually because the plan was written for the wrong reasons, in the wrong way.
The real purpose of a business plan isn't to impress a bank manager. It's to force you to think clearly about your business before you're in the middle of running it. The process of writing it — researching your market, working out your numbers, thinking through your operations — is often more valuable than the document itself.
A good business plan also gives you something to test your assumptions against. Six months in, you can look back and see where reality diverged from your expectations — and use that to make better decisions going forward.
And yes, if you're applying for a bank loan, a Start Up Loan, or investment from an angel investor or venture capital firm, you will almost certainly need one. But even if you're not, it's worth doing.
How Long Should It Be?
For most small businesses, 10–20 pages is plenty. A sole trader starting a local service business doesn't need the same level of detail as a tech startup seeking £500,000 in investment.
The right length is: long enough to cover everything important, short enough that someone will actually read it. If you're writing for a specific audience (a bank, an investor, a grant body), check their requirements first — some have specific formats they prefer.
The 7 Sections Every Business Plan Needs
Executive Summary
A one-page overview of the entire plan. Write this last, even though it appears first. Cover what your business does, who it serves, what makes it different, and what you're asking for (if anything). Keep it to one page — if a reader only reads this section, they should understand your business.
Business Description
What does your business do? What problem does it solve? What stage are you at — idea, early trading, established? Include your legal structure (sole trader, limited company), your location, and a brief history if relevant. This section should be factual and clear, not a sales pitch.
Market Research
Who are your customers? How many of them are there? What do they currently do instead of buying from you? Who are your competitors, and what are their strengths and weaknesses? This section shows that you understand the landscape you're operating in. Use real data where you can — industry reports, ONS statistics, Companies House filings for competitors.
Your Offering
What exactly are you selling? Describe your products or services clearly, including pricing, how they're delivered, and what makes them different from what's already available. If you have multiple offerings, describe each one. Include any intellectual property, proprietary processes or unique advantages you have.
Marketing and Sales Approach
How will people find out about you? How will you convert interest into sales? This doesn't need to be a detailed marketing strategy — just a clear explanation of your channels (website, social media, referrals, partnerships, advertising), your sales process, and how you'll retain customers once you have them.
Financial Projections
This is the section most people dread, but it doesn't need to be complicated. Include a 12-month revenue forecast (broken down by month), your key costs, and a simple profit and loss projection. If you're seeking funding, include a cash flow forecast too. Be realistic — overly optimistic projections undermine credibility.
Operations
How does the business actually run day to day? Who does what? What systems, tools or suppliers do you rely on? If you have staff or plan to hire, include a brief overview of roles. This section reassures readers that you've thought through the practicalities, not just the vision.
Tips for Writing Financials You Can Actually Defend
The financial section is where most business plans fall apart — either because the numbers are wildly optimistic, or because the writer clearly doesn't understand them. Here's how to get it right:
- Start with costs, not revenue. You know your costs better than your sales.
- Build your revenue forecast from the bottom up — how many customers, buying how often, at what price?
- Show your assumptions. "We expect 50 customers in month 3 because X" is far more credible than a number with no explanation.
- Include a worst-case scenario. It shows you've thought about risk.
- Don't project more than 3 years out for an early-stage business. Nobody believes 5-year forecasts.
- If you're not confident with spreadsheets, use a template — our business plan template includes a pre-built financial model.
Common Business Plan Mistakes
Writing it for someone else
The best business plans are written by the founder, for the founder. If you outsource it entirely, you end up with a document you can't defend in a meeting and don't actually believe in.
Ignoring the competition
Saying "there's no competition" is a red flag to any investor or lender. There's always competition — even if it's people doing nothing, or doing it themselves. Acknowledge it and explain why you're different.
Vague market sizing
"The UK fitness market is worth £5 billion" tells nobody anything useful. How much of that is accessible to you? Who specifically are your customers? Be specific.
Unrealistic financial projections
If your plan shows you hitting £1 million revenue in year one with no marketing budget and no existing customers, nobody will believe it. Conservative projections with clear reasoning are far more credible.
Writing it once and forgetting it
A business plan is a living document. Review it quarterly. Update it when things change. Use it to track whether you're on course — and to understand why when you're not.
Using Your Business Plan as a Live Document
One of the most valuable things you can do with a business plan is treat it as a working document rather than a finished product. Set a reminder to review it every three months. Ask yourself:
- Are we on track against our financial projections? If not, why not?
- Have our assumptions about the market changed?
- Are we still targeting the right customers?
- What have we learned in the last quarter that should change our approach?
Businesses that regularly revisit their plan tend to make better decisions than those that wing it. Not because the plan is always right — it won't be — but because the habit of stepping back and thinking strategically is enormously valuable when you're busy running the day-to-day.
Free Business Plan Template
Download our ready-to-use business plan template — pre-structured with all seven sections and a built-in financial model.
Get the free templateContinue your journey
Follow the full business planning pathway or pick up the Startup Handbook for everything from idea to launch.
Disclaimer: This guide is for general information only and does not constitute legal or financial advice. Always check current HMRC guidance and seek professional advice where appropriate.