Thanks for the replies - very true about the ebay things. Today I also discovered the petrol cap retaining cord had been snapped. They don't do the part on its own - you have to buy a whole new cap!
Anyway - since posting I have managed to find a friendly parts person at a VW main dealer. I intend to keep the car totally stock, apart from the head unit, as it is very well specced and low miles (37,000). My goal is to get as close to a "box fresh" GTI as possible.
Not sure that sort of car will be worthy of a readers ride thread but if any interest I will post up all the part numbers as it may help someone in the future. What do you think?
Since Tuesday night I've done around 400 miles and I am utterly in love with it. Brakes are insanely good (better than my 911) and the Xenons are incredible (ditto).
Thanks again.