In the hope to fix the brake bias, I've fitted quite basic EBC Ultimax pads to the rear.
I spoke to Vagbremtechnic who advised the M1155 pads are likely too much rear pad and the MC is unlikely the issue, so going to try a standard pad for now and hope they can just about cope with the temps!
Also checking the front pads it seems they've given up and just digging my nail into them slightly all the material is falling away...
I think I'll give EBC RP-1 a go now, PBS Pro Race is a very aggressive pad but the modulation has not been great so now I am running a standard rear pad I should be able to go for a slightly less aggressive front pad that is better suited to a more modern car in the hope for better modulation feel.