There can be only one choice - When The Wind Blows by Raymond Briggs. Yes, that's right, the bloke who wrote The Snowman. It's worth taking a second to remember the end of The Snowman, because it's not exactly happy, is it?
When The Wind Blows is the story of a little old couple in a little old house, preparing for nuclear war which then happens. It's hilarious and heartbreaking and so beautifully realised. It's the blackest of blackest humours.
It's also worth mentioning that sometimes Amazon's "Customers Who Bought This Also Bought" column is sometimes an utter delight: Customers who bought When The Wind Blows also bought a 500g bag of pink and white marshmallows, and a 48 sachet box of Felix As Good As It Looks cat food.