What's the school? It seems from your post that there is a little confusion about the difference between an ME (I assume you mean MEP) rating and an MEIR.
To answer your question, let's say you have a PPL and do a multi rating (MEP) - You now have PPL/ME. If you take your CPL on a single, your MEP rating 'jumps' onto that as well making you CPL/SEP&MEP. What (I think) you are talking about doing your MEP, then taking your CPL on an MEP as well (essentially getting your MEP rating twice) which is just about the most expensive way of doing things.
Now onto the MEIR: Just like the MEP, you can do it with a PPL and it 'jumps' on to your CPL when you get it. As long as you have enough XC PIC hours, it's probably better to do it before CPL. The other thing to know about the MEIR is this: you DO NOT need an MEP rating to get one. You have to do the training but you do not have to take the test or apply for the rating. You do not need to wait for anything to be issued before doing anything else: it's actually cheaper in CAA application fees to apply for CPL and IR at the same time.
If your goal is to work for an airline, the cheapest way is to first get an MEIR then go somewhere else and get a 15 hour single engine CPL (About £3-4k), and don't bother with MEP.
Last edited by rudestuff; 27th May 2017 at 10:12.