Yes perfectly feasible. I am ex L Tech AC left after 15 years and went to university as a mature student. My RAF qualifications were used as entry qualifications for my degree course. BEng in electronics and comms. I did my PPL after leaving at a flying club based at an RAF station. So do it, but take advantage of it. As others have said quite a few RAF stations have flying clubs.
Also think about doing a degree part time, if possible. If being a airline pilot is your aim. Plenty of universities do this but you do need to look around and you need to be in a location where you can regularly get the time off. Trying to do your OU whilst sitting in a damp tent in Denmark or whilst sharing a 8 man room in Cyprus makes it difficult when you are on a Sqn. If you work at 2nd line it is easier.
It does not hurt to do plenty of research.
good luck