I would be cautious about Beagle's statement that you don't need an MCC if you have an UK ATPL. Whilst he is technically correct, most airlines expect that you have an MCC when applying (unless you have time in a multipilot aircraft and no, dual checks in Tonkas don't count as multi-pilot!).
I think that you can do your IR renewal in a simulator these days and one option that I have heard about is doing the MCC and then asking if you can tag an IR renewal on at the end - this gives you time to refresh flying on a multi whilst doing the MCC and you can then get a reasonable price for the renewal simulator at the end. The guys at Leeds/Bradford were one of the names that I heard were up for the above scenario.
Basically the more qualifications/currency you can offer the better when it comes to applications - a major airline will not look at you if they have to put you through training to get the necessary 'ticks in boxes' - it is a competitive market out there if you are looking at a flag carrier airline (trust me that is the way to go!)