Cheers everyone, I did RTFM but was a bit concerned about wrecking them so sort advice form the knowledge of ukb. I also couldn't work out which bit the reserve tank cover was.
Opened the reserve tank cover, slipped the pads out, levered the pistons back, popped the pads back in, all hunky dory but the disc still catches ever so slightly. Going to have another fiddle.
What do people do when they take their wheel off in general? Do you put the pad spacer in to stop the pads self adjusting if you knock the lever?
Cheers for the help.