I don't do H.G.V but I know a few who do. You're gonna start out doing agency work (I think they call it general haulage) were basically you'll go all over the country chasing your load. It depends what you want to do, I think the good money is in long-haul (or tramping as some call it) P&O seem a good firm to get on for from what I understand, alot of what you do will be bonus based and that'll always be made that little bit harder to get.
I'm no expert on it, so don't take it as gospel, I think it's a good job for a single fella. Personally I like to go home to my own bed, that's why I work.
Good luck in your choices.