Yes - paying up front, without any clear guarantee (such as an independent escrow account) is dangerous and unreasonable - don't go there.
Whilst may of us, myself included, regularly advise against it for new pilots, given the Scottish weather had you considered doing a JAA PPL in the US (California or Florida usually) and then paying another £500-£1000 learning how to fly in British (Scottish!) airspace and weather when you get back (at wherever you are likely to base your private flying). It might well be cheaper and quicker.
G
Not flown at any Scottish school, so entirely neutral. But have flown around Scotland a lot, so know you'll not regret it in the long run.