MMC inc career structure in detail; MTAS; how the NHS differs to healthcare systems in other countries; organisation into and difference between primary, secondary and tertiary care; history (extremely briefly), eg. changes since Shipman; NICE and the QALY; what the GMC does; what happens when politicians play with the NHS eg. effects of the 4hr target.
Plus whatever issues are topical when you go to interview eg. polyclinics
A common interview question is, 'Who sets the exams for specialists?'.
The NHS does like its acronyms, doesn't it?