@RoyD - I wouldn’t necessarily say you need an invoice, it depends on your own circumstances.
If you have the paper records, then you wouldn’t necessarily need to record each one individually. Some people do it (myself included) so everything can be traced quickly and easily. But if you have £100.00 worth of fuel costs in a week and you have a receipt for each, there would be nothing wrong with bulking these together as one purchase invoice at the end of the week - as long as you have the individual receipts to back it up.
Always consider - if HMRC asked you to prove something, could you in the best way possible?
You could very well link straight from the bank to a nominal code if you prefer, but this doesn’t take into account VAT (if you’re VAT registered), and by creating a purchase invoice for it, you could probably find out more details quicker. An example would be:
You can do the same with sales too. There’s an article on that here