The Voyage of QV66
1978, Mammoth, London
A post-apocalyptic book about a group of animals who set off on a voyage in a little boat through the flooded remains of England. They are trying to find London Zoo and have many adventures along the way.
It's a cute book. I like how it was told from the point of view of the dog, and only gave hints as to what happened to the humans, without being a cautionary tale.
Link to journal at bookcrossing