...in addition to this, a bit of life experience would give you something to talk about during the selection phase! Believe me, there would be nothing worse than getting to phase 3 and dropping out because you have nothing to talk about!
By saying this, I am not implying in any way that becoming a Pilot or getting into CTC is an 'for those with age and wisdom' or anything like that, I started flying in NZ with them at the tender age of 21 and I was by no means the youngest on the scheme!
Also, as has been said, do look into university, not only does it give you something to fall back on, it does give you a taste of life away from home and ever more importantly, it also gives you a heads up on the kind of commitment to study that you will have to devote to those dreadded ATPLs.
I myself never went to uni and managed to get onto the course because I spent time productively after college. Also remember that being in an aviation related job isnt a prerequisite of getting in, it does help, and does illustrate your interest in the field of aviation, but just as equally important are jobs which flex your ability to show leadership, organisation, team work, etc etc, all the nice piloty things which would be vital in this industry!
I myself regret to a great extent not going to university, not only because I missed out on cheap drinks at the union, but also mainly because I stepped off that plane in NZ after moving straight out of my parents' house and felt very much in the deep end. Believe me, its one hell of a step up if you have never done it before and I found it quite daunting!
Every stage of the training at CTC comes thick and fast and my advice is get yourself prepared for it in advance!
Just food for thought mate, good luck with everything!
FBT