You need your business name and address, VAT number, any schemes you use, and — the part that matters — a digital record of every supply you make and receive, showing the time of supply, the value, and the VAT rate applied. What you do not have to do is scan and store every paper invoice digitally; the underlying document can stay on paper, it is the record of it that must be digital. Adjustments and the VAT account itself, linking your records to the return, also need to be digital. In practice, if you are using proper software with a bank feed and raising invoices from it, all of this happens without you thinking about it. The businesses that struggle are the ones maintaining records somewhere the software cannot see.