Hi, if you read through the sticky threads at the top of the B6 forum you can see most common faults and fixes reported to give you an idea what to look out for ..
Generally the 1.8 T is a good strong engine which can take 400 + bhp through it with upgrades and isnt a cause for concern as you going for the manual trans too its all good ..
My motors just hit 90k and runs just as sweet and quiet as when new. The key is to keep the car serviced reguarly especially the oil changes ..