Jobsa Guddun - best advice seen so far! If Joe wants to be a pilot, he should become a pilot! If, for whatever reason, a military flying career doesn't happen for him, better by far to go straight down the civil aircrew route than go for second (third, fourth etc?) best as an RAF EngO! You shouldn't deny yourself that which would make you truly happy.
This morning, I handed in my 1250 after 18 1/2 years as a member of the RAF Engineer branch. Spent most of it studiously avoiding jobs which had too much engineering content as I find it deathly dull and always did! Best thing I did... spend all my spare time flying, thus accumulating in excess of 2500 civilian flying hours.
As to 'where to EngOs go when they leave?'... my CV is getting sent to a variety of airlines during the next week... rumour is that First Officer recruitment is buoyant! :-)