Paying a large sum of money upfront is a bankers job. A banker would not lend 8000 euros to that school without any collateral and without having gathered a large quantity of information.
If your credit is better that the school's one, which is likely if you're able to pay the full training, they should rather place a deposit with you to secure your training than the other way around.
If the school needs to get your money before they have incurred any cost, it probably means that their financial position is not at its best.
On a regular basis, flight schools get bankrupt and students loose their upfront payments.