I've never had trouble with my rocker cover gasket but I would point you in the direction of Autovaux or Vauxhall World Parts. Both websites have been awesome to me (you do need to email Autovaux though). As for the cruise control, I have the same trouble. It's intermittent and random, it can go for months at a time without giving trouble and then go into full uncooperative mode for a while. I can't justify fixing it because the CIM modules aren't cheap and I won't go to Holden for reasons you've already experienced.