Cam the most important thing with a tdi you dont know,,,,,dont just do the tensioner,, one of the inherent faults which led to premeture belt failure was the bottom pulley, its probably already been converted, but be prepared to to shell out for a new bottom pulley, the new pulley has shoulders on to stop the belt wandering when the tensioner wears, you may have to go to a main stealer which will be around £80 for the whole kit, belt, tensioner, pulley, i'm unsure if the likes of paddocks still carry them?
?? you'll probably be luckier than me m8 and someone will have done it already lol, Tio