I would have thought you could go to see a UK AME and do another ECG between now and then so its valid along with your
medical. You could resynch it later and do another ECG with your next class 1 revalidation at the end of the year.
More money yes but that should sort your transfer concern I would have thought, I would certainly talk to your AME anyway.
My Class 1 Audiogram is out of synch like that so at the moment I just renew that on a different day when its due but will resynch it this year.
Regard's,