The GCR has a lot of stuff in it not normally used by drivers. The important bits are buried here and there. I have pulled together the rules which matter most in one small document. It fits on one page (duplex printing).
You can find it here: http://driverinfo.johnnesbitt.com/
I originally did this for operating stewards, but it's also useful for drivers. Of course, you are still governed by the entire 700-page GCR, but these are the rules which most often affect you.