What sort of self employment ?
All receipts for purchases of goods mobile phone house phone protective clothing household bills pens stationery office equipment ink cartridges.Tunnel fees fuel car repair bills. In short everything you buy no matter how you buy it market ebay etc new or second hand.If you buy something at a car boot Sale
make a note of site date and ofcourse the amount.
Depends on the sort of work that you are doing what type of spread sheet that you need,