When is the best age to join the military?

ok so i would like to join some british militate force. i am 16 years old am an air cadet and am doing a public services course which is basically all about the military and emergency services, at the moment im only on the course for one year but i can change it to two if i want should i stay with the course or join the military also what do you be leave i should join and what as i have some ideas in my head but i would like peoples personally opinions, i enjoy hand to hand combat if that is any help sorry if its not ooo and please no arguing over army and air cadets there both cadets things so don't argue about it here