James you shouldn't have been able to do that.
You need the MEP test cert in your hand you just don't need it issued.
Once you have the IR which will be a 55 hour course you only have to do a 15 hour CPL course.
I think it cost me only 350 quid extra to do it on the twin years ago with LFS.
There is an extended CPL course where you do a combined CPL and MEP.
From my experence after the IR the only thing which is extra compared to the IR was the visual nav. Which you can make life easy on by just flying everwhere at 120knts. All the other exercises are just a repeat of what you have done already apart from the engine failure which you look out the window instead of at the instruments.