Hello Tommy,
As has already been mentioned, the FAQs on the CTC website are perfect for naswering your questions; however, to save you some time, I an tell you that the pass rate of people on the CTC Wings course is 98.1% to date and, this far, 100% of those has been placed with an airline.
For the 1.9% who fail the course, for whatever reason, the full amount up to £30,000 of the training used will be paid by CTC as a "hands up" that they mis-selected on that occasion. What this means is that, if the cost of your training before you get sent home totalled £21,000, all of that will be paid for by CTC and you won't owe a thing. If, however, you have undertaken £41,000 worth of training, £30,000 of that will be paid for by CTC and you will owe £11,000. It is worth noting that this does not includeth foundation course - that is wholly your responsibility.
If you have any more questions, check the FAQs. They are VERY informative. if you can't find the answer there, feel free to let me know and I'll try to help.