Good write-up, Ben. Judging by the length and popularity of mazzy's thread, I think this forum can probably cope with another one.
A couple of things come to mind. You talk about a 50% share being for sale. Perhaps you shouldn't buy anything just yet. There are all sorts of things to take into account - what sort of flying do you want to do, do you want to tour and go fast, do you want something which is good for short fields, do you want to do aerobatics, etc etc? You may find all that changes as you learn more about flying. So why not wait a bit? There are always shares for sale.
On a similar note, you mentioned you'd wanted to fly helicopters for a long time. Now, I know I'm biased
but if that's what you really want, it won't just go away. I know quite a few people who got a PPL(A), then realised that it wouldn't quite do, what they really, really wanted was still to fly helicopters. Well, nothing wrong with flying both, which is why I still do that, but it's hard on the bank balance, and quite difficult to keep current on both too.
Anyway, your choice, but maybe a few things to think about.