Tyres.co.uk offers Michelin Primacy 5 and Goodyear EfficientGrip Performance fitment at 195/55 R16 91V XL that is factory stock for the 2023 A1 Sportback Sport 30 TFSI. Check the registration before buying. Make sure the load index, speed rating, and XL construction are correct.
To find the tyre size for your Audi A1, look on the B-pillar for the driver side, and find the tyre pressure placard. That will have the sizes of the tyres approved by the factory as well some recommended air pressures and the size that is fitted to the vehicle.
When you purchase new tyres for an Audi A1, you do not have to purchase all four. You can, however, buy them as an axle pair and fit the new pair to the rear. Most Audi A1 models are front wheel drive, but the A1 quattro is four wheel drive, and therefore requires all four tyres to have the same rolling circumference, tread design, size, and type.