The Magic Faraway Tree by Enid Blyton - one of the first books I can remember reading on my own without any help from an adult, I loved Enid Blyton books as a child and read them to my boys when they were small ;
Elf house on a tree! That would be cute in the garden, especially in the tree over grown with ivy. How about some battery tea lights in the windows during outdoor parties. I hear the fairies/elves whispering "home school project" in my ear.