Right lets see if I can make some sense:
This is for the cadet scheme, and I would say the most common way of financing as well:
You take out a bond for 60,000 pounds from HSBC. This gets given to CTC. You then go through all your training and start with an airline. After 6 months line training you then start getting paid a salary by the airline. (I believe you may get £1000 a month during line training by CTC).
This is where the bond repayment starts! They repay the bond at a rate of £1,000 a month for 7 years, as this is effectively your money there is no income tax on this so this is on top of any salary that you are going to get. It works out to more than 60k to cover the interest on the loan. Easyjet starting salary is about 21k with about 4k of sector pay on top.
If you completely ignore the bond then (as long as you work for them for 7 years) you effectively get the training for free with a starting salary of 25k.
If you leave the airline before that time I believe all you have to do is continue making the 1000 a month loan repayments but you will now have to start paying it out of your net salary after the taxman has taken a half decent slice out of it.
Not sure about ATP funding tho to be honest, sorry!