I remember having the GSGS map showing all UK airfields on my office wall at HQ STC in 1976 - it was very thickly populated. Tried to get another copy in the 90s, but it had been discontinued.
Whilst not a map, the following site gives current aerial views of sites of UK airfields most of which were RAF (or RFC or RNAS) originally. The link has been posted before on Pprune, but not recently.
Aerial Views Of UK Airports & Airfields