Welcome, kaytron!
There are two resources, but not one I'd recommend buying. Both are very expensive. If you can find either in a library, they might be of some aid to you. I don't find either of great use to help understanding TWHF, myself, but you might find some tidbits in them.
One is Bareface, by Doris Myers. The other is Reason and imagination in C.S. Lewis: A study of Till we have faces, by Peter Schakel.
Hope this helps.
Selah,
Sven
