Look, a couple of hundred thousand people commute across the border on the island of Ireland and there's huge cultural issues around basically everything. The Republic of Ireland would never be in a different timezone to the UK as long as part of the UK is on the island of Ireland. It's just not going to happen.
Yeah it was a big shock to me when I crossed that timezone between Chicago and Indiana.
Look, it's a cultural thing. The reason that we have peace on the island is due to constructive ambiguity. Half the population can pretend they're Irish, the other half can pretend they're British. Anything that makes that more difficult is not a runner.
Trust me. A 3 hour time difference could be the greatest ever efficency hack that would 10x the majority of your workforce performance (10x's stack for your 10x employees as well).
Trust me. You can deal with 3 hour time difference without even noticing.