Rachel, I have a guide entitled “Creation to Present: A Catholic World History Resource” and in this I see listed under historical literature (for the period you are looking for):
How the Reformation Happened (author — Belloc, Hilaire)
The Beginning of the English Reformation (author — Williamson, Hugh Ross)
Characters of the Reformation (author — Belloc, Hilaire)
These appear to be listed as high school level. Hope this helps some; not sure if these titles will be easy/difficult to find, and I have not read them personally, but everything else I have used from this guide book has been very decent living literature.
Blessings,
Angie