You didnt say what rank you were rejoining at.
My own tip is to remember the rank structure, arrive on time and keep quiet? It will take you time to adjust to the RAF way of life, its kinda like a civilian business mentality, but we wear blue uniform. We rarely/ shout, order people around etc.; people will want to do the job, because they like the job (and at times work beyond shift hours to finish a task). You will be around your senior officers, and its quiet easy to moan/complain without realising your skipping the whole rank chain... (unless intended).
You'll have plenty of options for sport, you can join one of the many RAF Sports Associations, attend Sports Fixtures for Station & Service (& civilian sport clubs), but also attend Service Overseas Visits / Tours every year. If your good enough for County, or National Level, then you could be selected for "Elite Level" and even then be posted into a special position to work with the GB team. Unsure if HWY (High wycome) has a Swimming Pool, if it doesnt, there will be cheaper entry to a local pool through the Stn Gym.
Accomodation, i would suspect you will move into Transit (bunkbed at worst, sink in room, communal showers / toilets) initially, then after a period of time (when it becomes available) you will be given SLAM (Double with En-Suite) accomodation. I think all accomodation has Washers / Dryers provided free of charge, and fast WiFi should be in every barrack block. If your lucky, you might even have a Sky Tv connection point / Tv Aerial point ~ as designed in 2005.
High Wycombe is 2 stations, the main site which is High Wycombe, but also Air Command (a seperate site). I am unsure if there are many juniors around, but there will be a lot of officers. Good transport links for London, most places except Norfolk...
Not many people drink these days, after work its back to the rooms, play online games or hit the gym/sports. Expect there to be minimum socialising outside formalised functions... if your in the bar every night, i suspect you could be the only one.
Then onto education, you can undertake University Short Courses, attend Courses at MOD Shrivenham, or even sponsored Masters / Engineering Degrees through the service. These should & must be self driven, as work will become a priority to some people, all work & no play whilst free learning is all free, and available to everyone. The courses are available through FDS (Force Development Squadron) / TDF (Training Development Flight) / LFF (Learning Forces Flight).
Joining as a Techie, you'll also get "Techie Pay", a bonus for being a techie in a techie role. Then we have the EngTech / IEng / CEng scheme, where you can get between £2k-£5k lump sum for registration (subject to rank)...
Now, if you fancy being an officer, there is always the Basic Entry Scheme to become either a Aerosystems Engineer or a Comms Engineer (Commisioned Officer). There is a IBN on the RAF Intranet about this. You undertake OASC at Cranwell, then off to Cosford for 14 months, into Cranwell for Officer Training, then back to Cosford for more training (whilst all being paid)...
I wish you well..