MCC ~ JOC
For the issue of your first multi pilot rating, you need to produce, inter alia, a MCC completion certificate from the approved training provider.
As a modular student, the MCC course comprises of 20 hours multi crew training in a simulator [PF : 10 hours & PM : 10 hours]. Five 4 hours sessions with a short break and seat swop after two hours.
If your course is 30 hours, it's quite possible that the JOC is embedded into the course. Speak to your training provider.
Although JOC is not a regulated course, a number of UK employers require a minimum exposure to multi crew simulator before the formal type rating.
Some would say that the harder part of the course is as PM.