You could contact one of the major charities who do "Free Wills". You don't have to leave them anything (but they like it if you do). They pay the solicitor a nominal amount for a simple will. Check also with your bank account, you may have provision with certain current accounts for such services.
If your affairs are uncomplicated, but all means do it yourself, but get a really good book to help you - "Which" publish a pretty good guide.
Sadly, I see more problems from home made wills than any other type so if it is even vaguely complicated, get a professional in.