One of the best resources you can use for learning about freelancing in the UK is run from right here in Brighton: Freelance Advisor. They have a active blog full of advice, and an excellent podcast. Their downloadable guide is an excellent place for you to start learning about the ins and outs of freelancing. It was written by Leif Kendall, a local freelance copywriter, and he compressed all the best advice from the first year of Freelance Advisor down in to an easy-to-read guide.
For more advice online, you can try the Professional Contractor's Guide (PCG) guide to freelancing, which is also good, if rather dry compared to the Freelance Advisor guide. For a brief one-page guide to getting going, try our own Freelancer's Cheatsheet, which is about as short an introduction as you can get!
If you like podcasts, have a listen to the Freelance Advisor podcast, which has interviews with lots of different freelancers who talk about the practicalities of the day-to-day work of a freelancer. My advice is to start at the first podcast and work your way through. There is some talk of 'IR35', which is some tax laws which might be about to get junked by the coalition, so don't worry about that too much right now. Just take in the general advice from people in the trenches.
As you're in Sussex, I strongly suggest coming down to one of the Brighton Farm freelancers meet ups. This is a bunch of active freelancers who get together once a week to swap advice, war stories, and bits of work. We meet every Wednesday in a pub in Brighton, and you can find us in the Wired Sussex events calendar. You'll be able to talk to both experienced and new freelancers, and you can plumb them for information over a nice pint. This is by far the easiest way to learn, and I learnt a heck of a lot this way when I was first starting out as a freelancer. Don't worry if you think you have daft questions to ask, we're a very friendly bunch and we've all asked daft questions ourselves in the past.
Freelancing and setting yourself up as a business can seem like a giant leap, but it's really made up from small, understandable steps. You can start out small as a 'sole trader' and once you're happy you want to stay working for yourself and become more successful, you can set up a Limited company if you need one. The main things to think about are: with a bit of help & advice, can I find work? Am I happy talking to people about what they need from their website? Am I capable of working without someone looking over my shoulder? Am I slightly more organised than a goldfish? If your answer is yes to all of these, with a bit of help and reading, you can certainly set up in life as a freelancer.
Paul Silver, Freelancer
You can watch a video of Paul talking about working as a freelancer.