Jeremiah in the Dark Woods by Janet Ahlberg

Jeremiah in the Dark Woods : Paperback : Penguin Random House Children's UK : 9780141304960 : 0141304960 : 29 Apr 1999 : Jeremiah lives in the Dark Woods with his grandma, who is brave enough to fight off crocodiles with her bare hands and her handbag. But her legs aren't so good, so when her jam tarts are stolen she sends Jeremiah into the woods to find the culprit.