I've been doing stage hypnosis for a number of years now.
Here what I've found:
Hypnosis is really just concentration, relaxation, desire of the participant and suggestion. In fact, we all go into a "trance" everyday.
It's like going to the movies. You sit in a comfortable seat, and you let the film take you: your heart pumps during the car chases, you may cry with the main charactor, you get into the story, and all during that time, you never hear the guy who's muching on his popcorn loudly two rows behind you.
Hypnosis is that, with the added suggestion from the hypnotist.
There are several books to choose from. Since you mentioned Derren Brown, I'll start with him. His book "Tricks of the Mind" I would HIGHLY recommend to anyone who wants to go into the field of "suggestion magic". His approach is very real and he's a skeptic, so there won't be any "supernatural" flim-flam.
Also seek out "The Encyclopedia of Stage Hypnosis" by Ormond McGill. That's a good prep book.
And also, you don't need a "College of Hypnosis" to learn how to do it. They are expensive and really don't give you anything you can't get with a little practice and some research. Hypnosis is a natural state we all put ourselves into every day: whether we are watching a movie, solving a problem, doing a repetative task, reading a book, whatever takes concentration, there's a point in which sometimes, the "outside world" fades away and you are fixated on something - and open to suggestion.
There are many ways to reach this "state of mind", and there are ways that one can help someone else achieve it.
Have any questions, feel free to pm me.