Faults to look for:

Look out for rust under the wing mirrors, and sometimes on the tailgate at the lowest point of the rear screen.

Get the inlet manifold checked for cracks, plus check the solenoid that activates the dual stage inlet manifold is firstly working, and that the connection cable between the solenoid and manifold is attached. The plastic connector is prone to breaking. Not something you can really check yourself but ask the garage to look.

Make sure the scuttle panel below the windscreen is a tight fit. It needs to be removed to replace the pollen filter, and many people have found pools in the passenger footwell due to incorrect 'sealing'.

Rattly gearstick and vibrating throttle cable are other things that can occur, but should all be fixable under warranty.

That's the main ones I've encountered/heard of. Good luck with the purchase, they're a great car to drive (so long as none of the above occurs!!)