http://www.businesslink.gov.uk/
Tons of useful advice here, government sponsored too!
Some quick tips though...
1. All businesses start with an idea, Once you have one, make a business plan. This should include your projected market for your business, details of competitive products/services on the market, set up costs etc. etc. Without a solid market your business is toast from the get-go. Your business plan will also be the basis upon which banks or small business funding organizations assess your profitability and whether they want to lend/grant you money or not. http://www.uknetguide.co.uk/Business/Article/Creating_a_Business_Plan.html
2. Keep your financial records accurate and backed up. Obviously recommending a computer-based system here. You'll need them if Her Majesty's come after you for the taxes you will owe them. On that note,
3. Read up on small business tax law and make sure you are clear on what you will owe, and try to keep up to date with it.
4. If you have close friends with skills you can use, you will probably find they are more than happy to help you from time to time, but don't push it! You don't want people thinking they are working for you without a wage. If they end up as excited about your idea as you, consider starting a joint venture. Be careful though, make sure the terms are laid out clearly and in contract so neither of you can get screwed over.
5. Create a relaxed yet focused working environment in your home if you are working from there. Energy saving lightbulbs are a good idea, they are less bright and glaring than filament bulbs and you are doing your bit for the environment and your energy bills. Invest in a comfortable office chair if you plan on spending a lot of time in it. Take regular breaks from working to spend time with the family, eat, drink tea and watch Countdown like any self respecting, tax paying, law abiding, BRITISH citizen. (Bit of an Al Murray tangent there, pardon me)
There's no point doing this if you don't take some enjoyment from it (even the enjoyment of drawing a mini-statement to check how much you've made).
Not sure if this is what you were after, but it should be fairly useful.
