Cheers. The best quotes I've got so far are:
£212 for GAP (Return to Invoice)
£312 for combined tyre/alloy
On my old S3 I used the tyre insurance twice. Complete replacement of the tyre each time and so it paid for itself.
I'll see what Audi can offer when I pick the car up next week. If they can get close to the above then I'll buy it from them mainly for the convenience.