There's nothing special about RAF bases - there are even special scenery addons - like control towers and hangars available that are based on old RAF designs.
Suggest you just download Airport for Windows and/or FSSC (the free airport design progs that we all use), do the tutorials and get going. That's what we all did - it's frustrating to start with but once you've got the hang of it, there's no looking back. Guarantee that within 2 weeks you'll be posting your stuff on Simviation!!

Roger