I am confused here. My expectation is that if I pre book say 10 lessons to get a cheaper rate, then why would cancellations outside my control mean I might lose them? Weather is weather, maintenance of aircraft is not my fault. If I don't turn up, I'd expect to lose out, but is there something I'm missing about the way flight schools operate?
Yes, flying schools are run on very tight margins and often go bust. When that happens, usually the students don't see a penny of their money back. It is also not unknown for students, for whatever reasons of their own, to decide they're not happy and wish to switch schools - and then for the old school to refuse to refund any money already paid, regardless of whether that's been flown or not.
Don't pay up front any more money than you can afford to write off.
G