One thing to watch: you will have to learn ICAO/JAR rules for the Air Law exam, which may be different from UK ones.
Actually that's the only real gripe I have with the Jeremy Pratt books. Particularly in Air Law he doesn't always make clear what the ICAO recommendation is, what JAR-FCL came up with, and what differences the UK introduced. In other words: What you can expect to be the same, and what can be different, when flying abroad.
From memory, this is something that you need to watch out for in:
- VMC minima, SVFR
- PPL privileges (particularly the restrictions placed on your license when you don't have an IMC or IR)
- Closing of flight plans, the whole concept of a "designated person", parent ATSU structures etc.
- Quadrantal/semi-circular rule
- ATSOCAS
- Listening squawks and other squawks (e.g. 7004)
- Booking in/booking out
- Joining a visual circuit