Completing a pre apprenticeship course is definitely not a requirement for General Aviation, I would agree it is for the airlines though.
In fact, many chief engineers Ive spoken to think the opposite, they don't like many of the graduates of these courses as they dont really have much useful practical experience.
Having said that, I did complete the aviation aus course in bris and it did help a little, mind you I think i could have achieved a lot more in the 10 months it took...