With the CPL/IR and a FI(A) rating you can teach all parts of the CPL course including the IF as you do not need to remove the applied instrument limitation for CPL instruction. As most of the CPL course is on S/E aeroplanes that should give you plenty of scope.
Standardisation training is in-house training to ensure that you teach in a standard way and may involve classroom and flying training but probably not more than 5 hours flying.
If you subsequently want to go on to teach applied IF for the IR then you will need to remove the no applied IF limitation. In fact it would be a good idea to do this anyway.
Getting the qualifying hours for the ME instructor course can be more difficult.