The only thing to bear in mind is the five year rule.
After five years with out renewing then you are required to do the renewal test with a CAA staff examiner. Other that that it is just training as required and a renewal test with any ME/IR examiner.
Actually you will find after instructing that going back to the left hand seat isn't a problem (where as when you when from left seat to right seat during instructor training it felt quite strange for a few hours).