Everything you need to understand or teach One Wish by Michelle Harrison.
After Tanya’s parents separate, Tanya and her mother head to a summer cottage near Spinny Wickett. Here, Tanya’s ability to see fairies leads her to the Wishing Tree where she meets a boy named Ratty. But when he disappears, Tanya uses her power to search for him, throwing herself deeper into the world of fairies than she ever imagined. This novel focuses on themes of friendship, consequences, and family.