It would be interesting to determine the depth and breadth of your loss of motivation, which now makes it imperative that you leave the RAF - as Terry Wogan would say - in a marked manner.
I think I would be 'doing the sums' very carefully first and would ask myself the question: is my loss of motivation and my desire to leave of such a level as to stop me seeing my normal time out with any reasonable expectation of job satisfaction?
If the answer is that you cannot possibly continue, you could always explore becoming a pacifist and joining the Society of Friends (Quakers) - but please don't do it just for selfish reasons. I don't support the Quakers but their beliefs are honourable and sincerely held and I accept their right to those beliefs.
Old Duffer