Hi a-wing.
You don't need an IR or MEP to be considered by most PPL flying schools, in fact many will see this as a good reason to hire you as they know you won't be clearing off to the airlines for a while. Our school will be hiring someone with just a CPL and FI in the next month or so, providing he passes the FI rating. By leaving the IR, MEP and MCC it will allow you to gain valuable experience and improve your piloting skills massively, making the IR and MEP easier to cope with.
Instructing is a great way to build hours and gain experience but as many will probably say if you do go the instructor route then make sure you don't do it just to build hours. Try your upmost to attain the best standards of instruction you can, and not just coast through until the airline job eventually comes along. I'm so glad that I went down the instructor route, i'm sure you'll have a great time.
Hope this helps,
Han.