If you really don't feel like studying then you do NS first. Change of scenery could do you good.
Pro: Change your prospective on life very quickly. After you spend 2 years booking in on a Sunday, you'll start to appreciate school life.
Cons: The set back is if you inspire to be an officer, you've got virtually no chance. Spec, only if you sign on. That's dumb too without at least a poly diploma.