There are lots of "common" faults with most cars mate, in reality you play a game of chance when it comes to seats - you either end up with a minter or a dog.
Things to look out for are:
water leaks from the doors/pollen filter housing
Rear wash/wipe works
engine light being on - temp sensor, glow plugs etc
turbo boosts fully throughout the rev range and doesnt drop into limp mode
engine start and stop faults - egr, asv etc
wheel bearings on the front
climate control screen function correctly
Also check the belt has been changed and service gistory is up to date
there are a few but dont let it put you off as most can be fixed both easily and cheaply.