Have you read The Hobbit, The Lord of the Rings & Silmarillion?
I find Tolkien a bit like Lucas in that he kept wanting to make changes, not always good, to his work.
These discussion threads on all things Tolkien may be of some interest, mate…
The OT.com J. R. R. Tolkien & Middle Earth Discussion Thread
The Lord of the Rings (Films vs. the Books)
There are also a few discussion threads on the films that refer to Tolkien and his books - listed up in the ‘Film’ category of An Index for Media : MySpleen, Film, TV, Music, Art, Books + Comics, Games, & Technology 👍