Sorry to hijack and bore everyone but CoolTurkey, to answer some of your questions (DP not here at the mo), he did a degree and went into European sales because of the languages but soon realised it was mind-numbingly DULL! He spent a few years doing bits and pieces then did a bit of labouring for a friend of a a friend and realised he fancied the idea of carpentry.
He was very fortunate to be taken on by a lovely, experienced guy who taught him everything about building in general. He then went on to work for himself and now either works solo on smaller jobs or employs labourers, plasterers etc for bigger jobs.
He loves the variety of work (something your DS might appreciate), the design element (when people want built-in custom-made storage, ideas for extensions etc) and most importantly, being his own boss!
On the down-side it is hard physical work, very unpleasant and unglamorous at times (digging foundations in cold, wet weather) and he never has time to work on our house .
Customers do really appreciate him. I think so many have preconceived ideas about builders being uncouth and uneducated that they are surprised. He has also never had to advertise as all his work is through word of mouth and recommendations so I guess hes really lucky.
CT -if your DS is enjoying the labouring maybe he should take a year out and do that to see if it still appeals after a winter of hard graft. If not, all is not lost and he can go on to college and maybe do something related like architecture where his experience may come in handy?
Good luck!