Guth
If you want it bad enough, you'll find a way to sort it.
I too, got average marks, but knew I "could do better if I applied myself" so... I studied at night time to repeat the subjects I needed for the RNZAF.
It's amazing what a little motivation can do to one's grades...
Good luck, but remember, there ARE other avenues and not everyone is designed to fly really cool fast jets
Kiwi Chick