i'll jump on the bandwagon aswell and tell you to stay for your a-levels - only because I have some experience in the potential risks you're essentially taking.
I was at school and wanted to join up, applied to uni (even though i didn't have the grades at the time) but had little intention of going. I did a sectt test (scottish trade test to allow you to do an electricians apprenticeship) aswell to cover myself. In the end, the vision in my right eye ended up in me being medically unfit.
So i was rejected basically. Not knowing what to do with myself, one morning the phone rang and it was the uni i'd applied to offering me a place. I took it because i had nothing else to do.
If i hadn't stuck that last year in school, the phone wouldn't have rang and I have no idea what i'd be doing with myself at the minute - at the time i hadn't found an apprenticeship (not that i'd looked

).
good luck, hope it works out
P.S (and not to hijack) Druadan... 9 weeks leave! alright for some, im sure you deserve it.