The Wilderness by Steve McCarthy

The Vasylenko family are adventurers. They all love the thrill of exploring the outside world. All that is ... except Oktober. He prefers the warm and safe comfort of the inside world, and for his adventures to take place between the pages of a book.

But, one day, Oktober has to join his family on a trek into the slimy, grimy and climby wild, where he sees only danger and worry and fears a creature called "The Wilderness"! Failing to keep his wits about him could be dangerous though – it may even get him a bit ... lost. But perhaps getting lost is just what Oktober needs to find himself and maybe even make an unexpected friend...