I went to place an order for one last week in June (with a tentative delivery date of 20th November), however a week later I discover that the dealer would not take the deposit off me because he says that VW will not accept the order. He says I'll be lucky to see one this side of Christmas (I think he means Christmas 2009!).

What??!! Find another dealer!
The first dealer I went to (on 4th July) said "three months, regardless of what specs you order." I placed my actual order with a different dealer (better discount) on 8th July, and he said "maybe September".
The second dealer also called up ready-built cars on his screen and offered me a choice of about half a dozen that I could have almost immediately, though I didn't bite on that one because he didn't have one with the specs I was looking for.
If your dealer can't sell you a car, there are plenty who will.
Rolfe.