The records I supply to my accountant are the dates I work plus what I turn over on those dates. Also, records of what I spend on my business, the dates of those expenses, and the receipts to back those expenses up.
In addition, for my own benefit, and for HMRC's benefit if they ever take a look, I keep records of individual jobs done. This is easy to document on a spreadsheet and print out later. My accountant is not interested in the level of detail that shows individual addresses etc. He just wants dates>amounts. That is sufficient so long as you keep a record of the finer details (for 7 years I think = 6 years plus the one you are currently working).