Last year I replaced all the bearings in my rear hub so they all should be sweet, Ive just put my rear brake line through my swingarm and reassembled the rear end only to find out when I apply the rear brake and rock the bike back and forward that Ive got a bit of movement before the brake works. Is this right? The movement seems to be in the whole of the brake assembly if this makes sense. Any help is appreciated, cheers Paul

Sounds like you've either got sticking pistons, your disc is too thin, or the caliper mounting is loose. Maybe incorrect spacers.

Did you remember to put the big circlip back on?!
Spring clips on the pads? Could be something simple in there.