Accountants, complete waste of money, but of course it does depend on how big a company/ complicated your accounts are. In twenty years of self employment I only used one for the first three years, and that was just to find out what you can and cannot claim for, and mainly how the accounts should be presented.
Even if you use an accountant, and the inland revenue decide to have a poke about, the accountant will just inform the inland revenue that they have only translated to them the information provided by you, so they are always in the clear, in other words you are on your own, so you may as do it yourself. Providing you keep on top of it, its not a chore.