I think the op is wise to question his decision, it shows a level of maturity that might be of some use.
I would challenge his view of isolated bases, the favourite example of Marham is 2 1/2 hours away from London and you have easy access to some of the best beaches in the country with all the activities you associate with being near the coast (except surfing perhaps). All the other bases have their pros and cons. In general the bases are not that bad, it's just all us old farts in here can't stop remembering the good old days, conveniently forgetting when we were young the old farts were complaining about how things have gone to the dogs, 'twas ever thus.
I would have thought a holding officer would have countless opportunities for AT, learning new skills and sports & developing their leadership qualities. How you perceive and approach these things will shape your experiences.
How can the flying not be worth it? Regardless of stream I believe that living and working on a Sqn brings a sense of belonging that is almost impossible to find elsewhere and when you go on ops, team spirit and sense of achievement is unparalleled.
To repeat two pieces of good advice, don't regret what you didn't do and whatever you do give it your all.
Whatever you choose good luck.