Hey Vandelay Industries,
I was in the exact same boat as you when I was in year 11. What i recommend you do is get in contact with a few people who have made it all the way through both worlds (civillian and military). Thats exactly what I did, and have been doing the last few years, and it has really helped me make that decision (which happens to be persuing the military). The insight of others is really helpful, and this thread is full of it, but remember at the end of the day its your decision and don't let people tell you what you should or shouldn't do.
What ever you decide to do stick to it 100%!