Welcome to the forum you'll find the members on here are a friendly and helpful bunch.
Check service history for proof of cambelt and water pump changes and gearbox services. Make sure ac works as compressors can be expensive.
Make sure the heater works consistently between all vents and heat is the same. If not it could be an issue with the heater matrix.
Issues with dpf, egr are well documented.
Check YouTube videos for buyers guides