ACC to a non-acc car

While it can be done this is a seriously expensive retrofit. As well as the ACC parts you need a new instrument cluster with ACC and a CAN Gateway with Extended CAN. If your soldering skills are good then you can open up your cluster and solder the relevant parts on but I would say you need to be an electronics god to do this.

Audi will not sell you a cluster unless it matches your own and MPH ACC clusters are rare as anything. If you do manage to find one, you will need to find a way of getting mileage adjusted and Audi will need to remove CP from the new Gateway, Cluster and ACC Radar as well as calibrating the radar.

Kufatec do sell a kit for £1800 and to be fair, even if you manage to source the parts individually I'll be astounded if you have much change from this after all main dealer work has been carried out. Wiring the system will be quite a task as well.

Something I'd like but just not worth the money and hassle.

It's a really good easy retrofit but very unnerving the first time you start the car and the dash lights up like a Christmas tree!