How much impact does it have when midday there's a blocker that requires interaction with the UK studios?

Happens all the time, it's a part of being a distributed company. Just have to include it in the handoff, and say we need someone to look at it tomorrow. Sometimes you say 'I know the person who normally does this is in the EU, but there's someone in LA who's familiar, lets ask them and try to diagnose, so when the person in the EU is in tomorrow, it's all laid out and they can just start working.'