Servicing is key. Any proof of major work too. Proof of gearbox oil changes and oil changes on the quattro system. Make sure all electronic items work such as AC as they can be expensive to fix. Also check out YouTube buyers guides
Under MOT rules MOT testers can only check the parts are fitted, not if they've been blanked out of the ECU. Garages are suggesting this as it's far cheaper than changing the egr.