Hi Joe
I have found Brembo BBK with 6 pot calipers and 345mm discs, front, for £3166 and a Revo BBK with 6 pot calipers and either 355mm or 380mm discs for £2035, these kits come with everything you need for a direct bolt on application and new hoses as well.
Looking at used prices of disc and caliper combo's that may fit are starting from around £1500, that is for RS4 discs and calipers, but doesn't come with anything else and I am not 100% sure if they will fit, RS5 ceramic discs and 8 pots are going used from around £3000 mark, again not 100% sure they will fit, both used sets would require a carrier bracket making or obtaining for the calipers.
It is looking like I will go down the BBK route just on a cost basis and the fact they are direct replacements without needing to modify anything.
Cross drilled and grooved discs and better pads is an option also.
Thanks
TooTired
T