Slim, its all about picking the trend in my opinion. At the moment the trend in our industry isn't very good.
I recommend you get a trade first, build some money up and then maybe consider flying at a later date. Believe it or not but you are VERY young and have PLENTY of time. Nothing to stop you getting to know the industry whilst getting that trade. Plenty of people on here are actually a help if you ask.
I've written extensively on this forum about this and other topics. I'm just saying what I would do if I was 18 again.
It wasn't long ago I was in your position (**** it was actually..). I fly in an airline now and its great but if I had my time over I'd have gone out and sorted a better back up plan. Right now I and many others are quite vulnerable. Our financial position is entirely dependant on passing sim (no problem if you study), passing the medical, industrial bastardry, fuel prices, the world economy and whatever good or bad moves our managers make.
Its uncomfortable to say the least when you don't have a backup trade.
The trend in this country is tradies doing extremely well. The trend in this country is pilots conditions getting worse and worse. Have a look overseas to see where it might end up.