Do a search on CTC. From as far as I can remember they tied in an MCC with a JOC and if you passed selection to get onto the thing in the first place and then proved yourself then you went into a hold pool. I think Oxford might run one as well.
I wouldn't advocate a JOC per se. What I would advocate was doing an MCC on a jet if you planned on heading down that route. If you want to fly a TP or something smaller then save your money and do it in something cheaper. Then keep your hand in and book a session in the sim prior to any sim rides you get offered following an interview.