If you type it into the search bar, you will see a thread I started in March about this piece. There were some really useful replies and suggestions, and I am going to buy Piano Adventures Popular Repertoire book 3A for my Prep Test pupil who wants to play it. She's currently on a lower Piano Adventures book, so (without having seen it yet) I would guess it might be suitable for your pre-Grade 1.
I'm going to set it as a "reward" piece for her to learn over the summer AFTER the Prep Test.