Join the army and save like feck mate, then when you get to the USA you will have the cash you need to do whatever you want over there, including doing an engineering degree there if you want as you'll have somewhere free to live at your folks etc anyway, if you join in the REME or similar you can even get some relevant experience
Personally I dont believe you will hack uni anyway, you'll get bored and not work hard enough, so I reckon you'll end up using the money from the army to start up some sort of business you can throw yourself into in the states!