If you want to do it in the US. you can start on the M1 visa, and do your private license +50 hours then go back to the UK for a vacation and change your visa to a J1 visa. That is no problem at all, as long as you don't have more than a PPL +50 hours, I did it, and some other people here at the school have done the same thing.
I don't think it would be a problem with your age, altough I heard about you have to be around 23 years old before you can fly offshore in norway.
Good luck to you with everything, it took me a busted knee and 3 months in bed before I decided to be a pilot
