You was just unlucky but also lucky to have the people around you that you did, I agree that having it inspected is a good idea and if possible not by the garage your buying it from, trouble is the v12 tdi is going to be extremely specialist and most won't know the common problems as there isn't enough about to be common.

Oh and scooby, iirc you have to weight ceramic brakes to tell the amount of wear and when a disc needs replacing.

Here you go
http://www.pistonheads.com/gassing/t...f=86&t=1099749