You may have clutch contamination. Are you sure that the clutch plate hasn't absorbed any fluid from the leaky cylinder? This would cause a judder.
As for the cam chain, Benny is the man to message for details on this. He's based in Wolverhampton IIRC. Loads of people from this site and VVOC have used Benny to do the work on their cars. Vauxhall charge over £600 but he is a fraction of this cost.
Daz also does the cam chain replacement and he's in Newport, South Wales. He did mine for me and a friend who I work with + many other members on here too.
;-)