Am I also exempt on the national license, and what evidence do I show the Examiner? Other than a UK Part FCL Examiner, who can sign the revalidation by experience on the national license?
Simply show the Examiner evidence of the LPC. Only a UK Examiner can sign a UK licence, as you are exempt the 1 hour dual FCL.945 is not applicable.
I am not 100% sure re the IR dates however; if one is based on the other then surely the dates must be the same.