Maybe not of direct use, but drawing on the experience of several years spent trawling around old airfields with my Dad in the '70s & '80s -
For sure during the '80s there was a series of books in print in the UK titled "Action Stations", there was a different book for each region ie Anglia, Yorkshire & North East, South East etc..from what I can remember there was - to an extent - a "then & now" about the books but not certain, prob worth a look anyway, for locations if nothing else. If not essential reading, close to it.
Also, not sure if the USAAF were in Sussex, but there is an excellent book called "Airfields of the Eigth, Then & Now" which even if you only have a passing interest in aviation history is a must, in particular WWII.
Living in the rural Countryside of Sussex myself I have a little tip for you, find out who owns the land and ask permission to wander around in advance, you'd be surprised as most will agree to a polite request and may also provide additional information that you otherwise would not have come across. Generally land owners only become agitated if you just chance it!
(Apologies for repeating information already contained in the last part of Tempsford's post!)