Hi Adrian, I found this page for the belt on a 2004 passat. Have a look and see if it's any use. I don't personally know what the passat looks like.
http://www.myturbodiesel.com/1000q/b5/serpentine-ac-belt-tdi.htm
http://www.myturbodiesel.com/1000q/b5/serpentine-ac-belt-tdi.htm