Does the MCC really expire? Its a certificate, not a licence or rating.
AFAIK all you need it for is to add your first multi pilot type rating onto your licence as per F4.1 of LASORS. Also a TRTO (or airline) may well have their own rules requiring you to hold the MCC prior to starting a type rating course. I couldn't see anything in Section F10 of LASORS that said it expired though?
From a practical perspective the better MCC courses have waiting lists no different from the IR and CPL training. Therefore timing will be important between getting a job interview/acceptance and having the MCC in the bag. Also you will have a hell of a lot on your plate doing a type rating so having the MCC out of the way will make life a whole lot easier.
You might decide to save some money for now and book yourself onto an MCC course when the market picks up. Depending on which course provider you choose this could have the added bonus of getting you back up to speed of instrument scans, holds etc prior to a sim ride.