You can take advantage of the simplified VAT invoice guidance available from HM Revenue & Customs, which applies where you make retail sales and you make a sale of goods or services for £250 or less including VAT.
When a customer asks for a VAT invoice, you can issue a simplified version that only needs to show the seller's name and address, the seller's VAT registration number, the time of supply (the tax point) and a description of the goods or services. A full breakdown of the goods purchased and VAT applicable is not required.
Where some of the items you supply in your business activities include items that are zero rated, for each different VAT rate your simplified VAT invoice must also show the total price including VAT and the rate applicable to the item.
If you accept credit cards, then you can create a less detailed invoice by adapting the sales voucher you give the cardholder when you make the sale. It must show the six pieces of information described above and you must ensure you keep copies of any less detailed invoices you issue.