A full VAT invoice must include a unique sequential number, your name, address and VAT registration number, the invoice date and time of supply (if different), the customer's name and address, a description of what was supplied, the net amount, the VAT rate and amount for each item, and the total VAT.
If you are not VAT-registered, you must not charge VAT or show a VAT number.
Example
Net £1,000 + VAT at 20% £200 = total £1,200, with VAT number GB123456789.