Surviving The Evacuation, Book 12: Britain's End - Surviving The Evacuation, #12

Anglesey became a refuge for survivors from across the world, but living in the shadow of a decrepit nuclear power station was always a precarious existence. There is only one destination for their final exodus from Britain, but Belfast won't become their new home. There are fewer undead on the island of Ireland, but their numbers still count in the millions. With farming impossible, with the weather worsening, with ammunition exhausted, desperation turns to despair.
All seems bleak, but the survivors don't know how truly desperate their situation is. During the chaos that ensued after the calamitous election, they misjudged the evidence. Their true enemy is still among them, and that enemy is about to act. Set nine months after the outbreak, in Britain and the island of Ireland, when humanity is at a crossroads. Either all will survive, or our species will die.