I've looked at the HM site previously, and tax isn't too bad to deal with (hardest part is keeping on top of all the invoices/bills so you have all the figures needed to fill in your tax return), however a good acountant should save you more than what they cost.
Other option is one of the many online accountants that cater to small buisnesses/sole traders.

Only reason I've been looking, is I should really be doing a tax return for the mountainbike guiding/coaching I do :whistling: