If you need to know the bonding situation, speak to rishworth as they are solely engaged in this.
Basically the amount of bond varies dependant on what you've flown before.
For instance for previous 73/75/76 pilots €30k, more for those with Airbus only, less for 777 I believe.
Either have the cash, or bank guarantee letter. If it s cash it is deposited in a bank account. 12 months after you start the TR you get 1/3 back with any interest accrued, another year and so on. No one is asking you to commit to anything financially until you have a firm contract.
I've had €20k back so far with no problems