Ian, your car may be fitted with 19" wheels but I'm sure it will not be a 19" space saver.
Space savers are tiny compared to normal wheels and look lost in the wheel arch on many cars.
Wheel bolt spacing and brake clearance for your car will be the main issue.
VW technical must be able to give some advice re what will fit.
How about VW Toureg, Audi Q7 or A8 space savers. Same family and large cars with large wheels.
If there is a spare wheel well, do they supply a space saver in other markets? If so a dedicated wheel must be available from VW Germany.
No luck, well try www.wheel-whores.com there's a forum there dedicated to guess what: WHEELS