I found them to be pretty easy to pick up when I first started, granted, that was with the last book... Lizardmen have a lot of diversity in the army list. If you want to have a lot of options, Lizardmen are the way to go. There are lots of different ways to build an army that will hel you to learn all the basics of
WHFB with ease.
For a decent start, I would get the book and a battalion. You get a really nice spread of units, not to mention you will save a nice chunk of change! The Battalion will give you 1000+ points to play with. Look through the book, see what you like and keep building from there!
If you want to read more there are a few decent site you can look to.
http://www.lustria-online.com/
http://www.pyramidvault.net/index.asp
Both are decent, look around; there are some decent discussions over how Lizardmen work. Other than that, reading over some basic tactic stuff for
WHFB in general is a good idea, too.