Here's a brief reality check for you:
1) With over 3000 short haul cabin crew and 1000 short haul pilots I rarely go to work and fail to see someone I recognise from somewhere that I've flown with. Try saying hello to someone you recognise. Now I'm on long haul I see a load of faces I recognise from short haul or other long haul trips. Its a job, not a social club, and as you've never worked anywhere but BA, let me assure you that if you work in any other job it's equally unlikely you are going to be drinking buddies with your workmates.
2) BA does not take over your life unless you let it. Claiming it's very very hard to keep in touch with people in a 9 to 5 job is an exaggeration. I managed it when I was working every weekend and commuting long distance. Try doing something other than the massive Friday night out. I see most of my 9 to 5 mates on a weeknight for a few beers after work. I can have lots, they can't. Bonus for me.
3) Thats the way of life. I doubt it'll be much different elsewhere.
Remember everyone looks back on their days elsewhere through rose tinted glasses. I certainly remember the piss ups and parties at a regional base, but I'm prone to forgetting the utter tedium of doing the same limited routes each day, the lack of nightstops, the sheer grind of the hard work. The few cabin crew I know who left BA looking for better either quit the industry all together or came back to BA, even the ones who went to the so called party airlines. The grass is always greener, and when you find yourself in the kebab shop downroute at 5 am with yet another disgruntled Virgin crew member telling you what a bunch of miserable, catty, b1tching whingers they're flying with you'll begin to realise that.
As for making your own entertainment, here's a suggestion. Next night stop ask the flight crew where they're going for a beer. If you don't like that, go out on your own to a bar, sink a few beers and talk to some locals. Works for me.
PS You might be pleasantly surprised at the social scene on long haul. Life's what you make it.