What the fuck were Garland and Boyle thinking?

How did the rest of the world just move on? What's their discourse about the UK like?
Why was Spike confident enough to take his dying mother into the mainland when he barely survived with his experienced father?
How did Spike not wake up to the noise of his mum smashing a zombies head into stone?
What were Swedish soldiers doing on the mainland?
Why isn't the baby infected?
Why didn't they kill Samson after he was sedated?