Thanks to Karen for sending me this information.
I have just applied for the NHS app to show my Covid status.
Got a message saying it will take 7 days to process , so people need to apply now if they are travelling soon.
The government website tells you that you need to apply for this app, and I would think the more people applying the longer the status will take to show.
You also need to Allow the app access to your phone and camera, as you need to video yourself saying four numbers that they send you. This is obviously to prove you are the person who has had their covid Vaccines.
If you don’t allow the NHS app access to your camera you get a black screen when you try to do the video, and this is not accepted.
Hope this is of some help to all UK travellers. Put a comment below if you found it straight forward or not.