So the moat has been made into a beautiful garden.
The castle's "chapel" is a full-sized freestanding church, but it does seem small in proportion to the castle and its grounds. Wikipedia says "It is both a royal peculiar and the chapel of the Order of the Garter."
I love terminology like "a royal peculiar." The only photos I took were of this peculiar (yet familiar, because I've seen him in books) guy: