I didn't fly for 7 years. It took me two training sessions - one upper air, one circuits, then I went for a GFT with an examiner. To re-qualify in 3 sounds like a brag, but it was the sweatiest 3 flying sessions I've had.
First port of call is your favoured flying school, especially the CFI.
Secondly talk to the CAA. You may have to decide which licence you want to go for. NPPL or EASA. There may be additional competences to be demonstrated. It depends on the aircraft you wish to fly. The modern plastic NPPL types are now extremely civilised, quick, safe and frugal. Changes to the Medical are primarily for NPPL, I gather.