I think I'm correct in saying that,if you still maintain your ATPL, then you already had an IMCR by grandfather rights.
You are referring to a UK ATPL not a JAA ATPL!
If you renew your SEP(Land) by experience next time, tell the Instructor you'd like to do your 'hour' as instrument flying, just to keep your hand in.
If you hold a professional licence and do LPCs you don't need an hour with an indstructor!