I went to a smallish school at BOH airport on the sunny south coast (allegedly
) of the UK for my ME, CPL and IR. From memory I think it was Friday that was their pay day. We would each get a statement of our weeks flying costs and duly handed over the credit card. Note how I said cc and not cash or cheque. Therefore you could cancel the transaction if you ran into any problems in the forthcoming days. All that they required you to do was to be in credit at any time. In reality most of us kept a few hundred quid in credit with them but if we owed it was never really a problem as the card was always there to be handed over when we were back on terra firma.
Don't believe all the marketing mumbo jumbo that these "big" schools put out. It IS NOT normal to hand over large sums of cash for a service that they haven't yet delivered. Nor is it the norm in any other walks of life.
Ask them if they have paid their instructors/rent/maintenance/fuel etc six months in advance to substantiate why they need so much cash up front. Its purely a ploy so that you won't leave when things start going pear shaped. It is also a classic sign of insolvency which I saw time and time again when in my former life I worked as an accountant.
I would also hasten to add that with costs spirallling and the number of trainees potentially falling that some of these schools could well fall onto hard times. Which gives more reason for them to want your business more than ever and for you to drive a hard bargain.