Brake disc change ATE or Girling calipers?

[cerbrus2]

Sorry for the noob question but,

I have a 54 plate A4 Cabriolet, and need to change the discs and pads on the front. I have been looking on demon tweaks, and they have 3 different sizes for the discs. but also 3 different manufacturers of Calipers. ATE, Girling and TRW, I am assuming this is for what set of pads they send with the kit. does anybody have any idea what sort of calipers they put on mine?

 

Model is A4 B6 cabriolet sport 1.8T