I don't believe there's specific legislation for work from home if it's just a 'few hours per week' (or whatever you do) but you may want to look at the health & Safety section here:
Working from home : Directgov - Employment - that also has a link to the H&S at work page. You may also want to check if you need any liability insurance for yourself or any other members of staff or customers that may visit (if they're likely to) your home, from my memory of UK legislation I don't think it's necessary just for you.