Current theory seems to say that the tune is too old to be Henry's, and the words are too new.

(Though even if he did write the song, his marriage to Nan Boleyn the Witch was part of his efforts to return the British Crown to the original Plantagenets' adherence to the Old Religion, so you can still pretent it's a Goddess hymn. ...At least that's what it says in one of my Big Books of Wicca, so it must be true. :P )