For a small business, you should be able to get away with Excel
and a smart Excel template. Many accountants will give you a template
they use.
They need a record of all expenditure, and if it was taxed and at what rate.
They also need a record of all sales, and if you charged VAT. From this, they
can work out your VAT3 Returns. Many excel sheets also break things down
in to the categories like "Transport" related costs, "Telephone and Office" etc. But at the year end, they will also need a copy of all your hard copy bank statements to reconcile these with whats in the info you give them.
I guess it depends on your transaction volume, and if you think Excel and you
can handle this in Excel.