Apologies if you've tried this, but I'm long retired and NHS App wouldn't connect me to my long time civvy records. Think a helpline number popped up when installing App, called it, and transpires the Surgery have to be told by you to make records available. They're not automatically in the ether. Couple of hours later while 1's nd 0's did their thing and all sorted.
As I say, apologies if you've tried this and RAF/Military Med Centres not part of greater NHS which is a whole other debate.