The Wee Free Men by Terry Pratchett
Tiffany is the granddaughter of Granny Aching, a wise old shepherd woman. She doesn’t realize that she is a witch-in-training, destined to take Granny Aching’s place, watching over the land and the people of the "Chalk," until the Queen of the Elves kidnaps her little brother Wentworth.
Armed with courage, a frying pan, and a book of sheep remedies, Tiffany goes off to an icy, nightmarish Fairyland to rescue him. She is accompanied by a toad and the Wee Free Men (of the title), also known as the Nac Mac Feegle or pictsies. The Wee Free Men are a clan of 6-inch-high blue men, who love “fightin’ an’ stealin’ an’ drinkin’.” They enthusiastically use all of these skills to help Tiffany find her brother and take him back from the terrible Elf Queen.
I listened to the audio version of this book, read by Stephen Briggs. He was absolutely terrific at bringing the characters to life, from the thick, barely understanable brogue of the Wee Free Men to the whiney wail of Wentworth, his voice added immensely to what was a great fantasy adventure tale.
I'm looking forward to reading (or listening to) Tiffany's next adventure.