Who submits your VAT returns?
If you have an accountant who does that on your behalf, they ought to keep a copy of the VAT submission receipt for each quarter that they file the return for. If they haven't kept a copy ( which they are meant to ) then they can log into HMRC and print the submission receipts for the return for the last 5 quarters - this will have your business name or your name if you are a soletrader, registered office, VAT registration number and all relevant boxes figures which was filed.
Alternatively, if you file your VAT returns yourself, you can print the same by logging into
https://www.gov.uk/log-in-register-hmrc-online-services
Choosing VAT
Log in using your government gateway id and password
Hope this helps!