Just completed it took 10 minutes.
Before you start you need a photo ID ie passport .
Your Nat Health Nos its on your vaccine paperwork .
E mail address and mobile phone number for just in time verification purposes.
It will ask you to take a clear photo of passport .
You also will be asked to do a video of you speaking 4 numbers .
https://gov.wales/nhs-covid-pass-prove-your-vaccination-status#section-73757
Both of the above are uploaded via the link .
Do it in a quiet moment.
Good luck .