Check wheel and tyre condition and that all four tyres are the correct size (rears are different to the fronts usually)
See that the roof operates reasonably quickly, ideally see if the motor has been relocated to the boot.
Two keys.
See if the clutch delay valve has been removed on manual cars.
Make sure its the spec you want. Heated electric seats, cup holders, MFSW, Nav, auto headlights etc etc.
Make sure the boot floor, the battery well and the carpet in the cabin is bone dry (check behind the seats).
If its a hot day see if the steering feels sticky.
If its not got a new advisory free MOT check that any advisories on the last one have been dealt with.
If you can try and get an idea of how old the shocks and struts are, 50,000 miles is about as much as they will do. The MOT no longer has a bounce test to tell if they are knackered so as long as they are not leaking they will pass - but they will be knackered!
Check for lips on the disks.
Check the ratchet on the handbrake lever feels okay and stays up of you give it a bit of bang. The handbrake isn't great but it should hold the car.
The only places they seem to rust are around the wheel arches and very occasionally down at the bottom of the rear wing just behind the trailing edge of the doors.