Thanks for all the comments so far. I must add that I have been doing research into the Navy but only via their websitem which to be fair, is comprehensive ... i think.
I took their trial apptitude tests and got 100% pass although i suspect its just a taster test as its quite easy.
The major thing for me is being away from home. Not so much home as in Aberdeen, but more my girlfriend and my life. Thats the only thing stopping me walking into the recruitment office tomorrow. How do people get around this? Do they just give up everything?