I think the best advice is hope for the best but be prepared for the worst.
That's not me being negative, I love my L322 but you need to be realistic, things will go wrong.
Mine is an earlier td6 so some of the issues may have been sorted on later models.
I'd check steering wheel rake, if it works on the motor up and down great but if it has free movement up or just drops down then it can be an expensive fix,
Rear wiper motors are a prone failure I fixed mine for £70
Dash pixels can fail I believe £100 will fix this
Door lock issues and folding mirror issues are a cheap fix
Rear bushes are prone to wear but aren't expensive and can be done with a ramp
Other than an engine issue I've fixed all the faults cheaply and without needing to go to a garage, you will need a diagnostic tool but I bought an icarsoft reader for £100,
My car is high mileage 230,000 but has been well serviced so personally I'd go on condition rather than trust any paperwork.
I'm sure other people will try to put you off but if it's nice and it's a good price then buy it and enjoy it, just don't get down when something fails, all modern cars break, and are expensive to fix, just be smart where you spent the money