Fairly straightforward - ask the Med Centre, the Regional Practice Nurse would be a start, if not the SMO. If not there then the Command Flight Medical Officer (CFMO) based at RAF Henlow or maybe the senior doctor at the Department of Occupational Medicine at RAF Cranwell (which is part of OASC). There is also a Medical Casework Doctor (civil servant but ex-RAF senior officer) at HQ Air who deals with such stuff. I’ll not mention known names for obvious reason, but anyone with MODNET access can find those.
Good luck. The one thing all Aircrew can guarantee in life is that eventually we all lose our medicals. Some sooner than others, but it’s a fact of life. It sucks.