I think you should rest assured that your money (although quite a lot of it) is well spent at Oxford. If you have the ability and commitment to become a pilot then Oxford will help that become a reality. I think one of the biggest differences between Oxford and elsewhere is the instructors seem to be mainly ex Airline pilots themselves or at least pilots with a huge amount of exerience rather than some recent graduate hoping to build some hours before going on to bigger and better things.
With respect to availability of planes and scheduling I think it comes down to luck and whether or not your instructor pushes for them, getting his bid in early. If he's not so efficient you can always push for slots yourself, its no big deal. Of course aircraft do sometimes go tech and there's not a lot anyone can do about that but thats going to be the same story the world over, thats the nature of the business.
Throughout the course its important to get as many first time passes in anything that you can, the less retakes of anything at all you have the less reasons Oxford will have to not put you forward to airlines at the end of the course! With the airlines setting criteria they can afford to be pretty picky with the mass of unemployed guys and girls out there.
I'm not sure quite why OAT get such a bad press especially on here and mainly by people who haven't even been there! Oxford offer a damn good quality course and charge a permium price for it, its as simple as that. You wouldn't fly BA and expect to pay a Ryanair ticket price would you. I'm not saying its perfect by any means although in my experience they do take feedback on board and attempt to address any issues that arise.
Unless you're incredibly lucky wherever you train you're going to end up in a lot of debt, I personally think its worth the extra because of your job prospects after. Its all very well saving 20k or however much but if you're unemployed for a year or two after you might just pay most of that in interest before you can start earning serious bucks to pay it back. If I had to do it all over I would go to OAT again without a doubt, I cant say I didn't have single reason to complain while I was there but I can say I was happy with the overall package.