UKPassats

So as per title has anyone bought one of these and fitted it to a car that came without a towbar I accidentally bought the witter removable one thinking it was for my b7!saloon ended up accidentally ordering a b8 estate towbar so need to get the correct one. Am I right in thinking if I buy the bar and the genuine trailer electronics module it’s just coding with BCD’s or is there more to it and other modules? Also is there a switch to lower it somewhere needs fitted?