In view of the current rumours of an impending 25% cut in RAF personnel, I wouldn't be too sure that your pay from Aunty Betty is as secure as you'd like to think it is! Since 1990, the RAF has reduced from 91,000 unformed personnel to its current level of approximately 50,000. Much of that was achieved by voluntary and compulsory redundancy. There is no reason to believe that any further reductions would be handled differently.
In that light, you may want to revise your thinking about retraining for another career; it may be forced upon you! Looked on from that perspective, you may feel that entering ATPL training is less of a risk than you thought.
Scroggs