Thorpey,
Interesting plan of yours, and best of luck if you give it a go. One thing that springs to mind though is that rearcrew jobs in rotary (and I daresay ME, though I don't know first-hand) are very physically strenuous, and a 20-something is better able to cope than a 40-something. Bear in mind that the RAF likes to sign on aircrew for a reasonably long engagement, to recoup the training costs, meaning that you might end up doing the job in your 50s. But don't let me put you off trying!
TOTD