Your General Practice is unable to offer you a certification of
Proof of your vaccination status will be available on the NHS app, NHS website or contact 119.
The NHS app can be downloaded from https://apps.apple.com/gb/app/nhs-app/id1388411277 for iPhone or https://play.google.com/store/apps/details?id=com.nhs.online.nhsonline for android. This app is also valuable for accessing your health records and ordering repeat prescriptions.
The NHS website: https://www.nhs.uk/conditions/coronavirus-covid-19/coronavirus-vaccination/vaccination-status-for-travelling-abroad/
You will need to register to use the online services, if you have not already. It may take more than a week for your identity to be checked and verified.
Alternatively you can call the NHS helpline on 119 (from 17th May) and ask for a letter to be posted to you. This must be at least 5 days after you’ve completed your course of the vaccine; the letter may to take up to 5 days to reach you.
Please see https://www.gov.uk/guidance/demonstrating-your-covid-19-vaccination-status-when-travelling-abroad for further information.