I don't know a spell to turn you into a fairy, but I know one to let tiny fairies rest in your garden at night. At night, fairies get tired from flying and need somewhere to rest and have a drink.
Find a safe place in your garden or somewhere outside where they can rest. Leave a small saucer with a little bit of water in it for them to drink. Now you need one yellow flower one blue flower and one red flower. Mix their petals together and sprinkle them around the saucer. Draw a star around the saucer on the ground and say the following spell:
"With flowers yellow, red and blue
I make a meeting ground for you
so fairies come from north and south, from east and west
and find this star a safe place to rest".
If in the morning you find that a little bit of the water has gone, then you know the spell has worked and fairies have used your hideout. good luck.