I've just had the following response from SEAT:
"This can upgrade can be bought with the vehicle from a SEAT retailer at the point of purchase or added after market by the customer.
If a customer ordered a
CUPRA Ateca Limited Edition, it would be built as a ‘normal Limited Edition mode’ and then when it arrives in the UK, the upgrade is added by Richter Sports in Bletchley.
This protects the warranty of the vehicle.
ABT upgrade can be added to any vehicle aftermarket, however it’s only on the Limited Edition model that it can be purchased via the retailer."