If you've read Graham Duke's ATC book - a very good introduction, although a little dated until the new 10th edition comes out next month - you've probably got a good picture of ATC and how it works.
I don't know if there's a book like 'Aviation for Dummies' (!) as it's a huge industry, but Flight International magazine (and the other magazines in the same place in the newsagents) is probably worth a shot - it reports news about all sorts of aviation related things - manufacturers, airlines, ATC, routes, etc etc.
I don't know if it's possible, but if you could get a week's work experience at an airport, you might find that interesting if they let you visit ATC, Ops, and other bits too.
There certainly isn't a requirement to be a real aviation enthusiast to be a successful NATS applicant and eventually ATCO - I'm definitely not a planespotter although with my aircraft recognition preparation for the college, I might be becoming one!
Hope that helps a bit...