For a 2008 car you have a chance of having 2 different types of the 4 pot caliper being fitted to it. You could have the 260CUP setup P/N CP7624 which is the same caliper as you can get in MG ZF’s or the later 4 pot setup which has the p/n of CP7635-2S0BG:LOT for RHT CP7635-3S0BG:LOT for LHT.
The easist way to tell is if the caliper bolts directly to the upright or not. If its a direct bolt its CP7635 if there is an adpartor bracket it CP7624.
As for fitting bigger discs you will have to get spacers between thwe caliper and the upright to space it out for them to fit.
If my memory serves me right, both calipers have the same piston sizes so the kit you sent will likly be fine for both. the difference are in the width of the caliper the CP7624 is wider, takes a 16mm brake pad instead of the 14mm of the CP7635 so the anti rattle plate and pins are different.