[HarryT]

The book you're describing sounds very like "The Borrowers Aloft" - the 4th book in the "Borrowers" series. From Wiki:

Spoiler:

With the help of their friend Spiller, the Clock family have relocated to the miniature village of Little Fordham where they try to live in secret. They were discovered by a couple who own a rival model village and are kidnapped with the intention of being put on display as an attraction when that model village opens for tourist season. Imprisoned through the winter in the couple's attic, the Clocks are able to use materials they find to create a balloon and basket which lifts them out of a window and to freedom before they can be put on display.