under JAR:
you need 200hrs IFR (50 hrs can be in FNPT2) to be able to take a course and a skill test to be allowed to teach for the IFR rating.
you need at least 10 hrs as PIC on ME-piston in the last 12 months to take a course and skill test to be allowed to teach for the ME class rating.
you do not need to take a seperate course to teach for the CPL, it is just a matter of instructional hours given, I think 500 but I am not 100%sure on this.
UK regulations might be a bit different, check out the ontrack website. You 'll find all this very clearly explained.
www.ontrackaviation.com