If you were chopped from pilot training, and you had good a-levels, what would prevent you from starting uni aged 21-23ish, with the view to going on to a top job later on?
At least you would have had a go at flying in the military, had a pretty good time on the way, realised it wasn't to be, and you would then have 3/4years of fun and debauchery at uni to figure out what you want to do in civvie street.