GREAT choice: I've the A1 supercharged/turbocharged/7-speed DSG (so lots of low down torque) variant on 18-inch rims with Toyo Snowprox winter tyres fitted and for sure during the recent snow and ice road conditions the traction, steering, and braking has been near perfect. Didn't bother getting the quattro machinery (TT and RS3) out of the garage. Ok, just for exploration you'll understand, I did explore the traction limits and was impressed, mightily impressed at the traction afforded by the Snowprox and the A1's electronics.
The Snowprox now on their 3rd season, shortly to be swapped with summer rubber and carefully stored for November 2018.
Why others refuse to accept the safety of such tyres in UK winter conditions I'll never understand....
Make 'em a legal - insurance wise - requirement, I say!
Stuff it in sub 7ºC conditions whilst wearing summer rubber and it's 3rd party insurance for you!