There is a free video series on VBA Programming by Steve Bishop on Youtube. It has over 70 videos --all well done.
The series playlist is
here.
I looked for a book with some specifics on Class Modules and did not find one. I have found that some of the older books Access Developers Handbook 2000 or 2002 were quite good with vba and had useful examples.
I did buy (used via Amazon) (Hennig/Cooper/Griffith/Dennison)--it's about 1200 pages and has lots of info.
Watch some of the video before buying anything.
Good luck.