Firstly, you should ask the school doing the check, that way you will find out for sure what they intend to do. In the main they will check your ability to operate their aeroplane, that means basic manoeuvres:
Stalling
Steep Turns
UPs
PFL
Circuits
EFATO
If you don't hold a UK issued licence they should be interested in you radio work and knowledge of UK Rules/Airspace.