The Ebony Tower and
The Magus were also made into a films; the latter did not do justice to the book and, apparently, Fowles thought it a disaster. However, I value it for two reasons: firstly, it alerted me to the existence of Fowles and secondly it made me read TS Eliot (there are some lines from
Little Gidding in the book).
There were also other novels:
Daniel Martin,
A Maggot and, my favourite:
Mantissa.
If you think Fowles is "difficult", try John Cowper Powys -- I see him as a sort of cross between Thomas Hardy and John Fowles with a bit of the warlock thrown in for good measure. Fanatastic writing (in both senses of the word), but tricky as hell!
Wolf Solent,
A Glastonbury Romance or (especially if you are interested in Roger Bacon)
The Brazen Head would be good places to start.
--
Stephen