Your situation sounds a lot like mine Im doing my a-levels at a secondary school sixth form highschool, the people are not my people, my subjects, sociology, psychology, and philosophy are a little too academic for me and I have no interest in pursuing them as a career at all. I want to drop out and do an aprenticeship, I hate school and want to start something new and a step up as I see it. But my parents don't want me too, I'm sure they would understand.
The school environment is depressing, I too submitted an application to join the forces, I chose navy to travel and be at sea. also to train as an engineer. The subjects at school have no meaning, I like you coasted my way through the first year by getting by on the bare minimum. I think leaving would be the best thing for me.
Do you have any reasons that's stopping you from dropping out, mine are just fears that have been drilled into me by my parents.