I think #2 is the important one. Get a Class 1 before anything else. If you cannot get a class 1, then that's it anyway. Then get a second opinion on your back and maybe a third. If the medical advice really is not to fly then you'd be fairly daft to ignore that. But spend nothing on anything else until you know exactly what your medical position is.
As for the rest, it is a case of thinking about how much you want it. You don't say if you enjoy your current £80k job, but if you do then i'd think hard about just getting a PPL and spending the £70k on a share in an Extra 300 (or whatever else appeals). You can have an awful lot of fun with a PPL. If, on the other hand, being an airline pilot is the thing you've always wanted to do then go for it. You've got the money, it may not happen (look for posts by WWW on how many people never make it from fATPL to F/O) but you have a chance to try.
...and ignore what Oxford are saying. In the end they're trying to get you to spend £70k (or whatever it costs) with them
