I'm doing ACC and AVFTB. I looked at the past papers on WJEC website so because of elimination and looking at main characters and themes:
ACC could be
Characters - Scrooge (obviously), Bob Cratchit, all Ghosts (and Marley) or Tiny Tim (and fezziwig but he is a minor character so very unlikely to come up)
Themes - Isolation, Transformation (easy one so hopefully will come up), choices, time, home, memory/past and guilt/blame
AVFTB could be
Characters - Eddie, Catherine, Beatrice (the rest have all recently been focused on but could still come up as part of a theme)Themes - Justice/Law, abandonment, masculinity, respect/reputation, women/femininity or hopes/dreams.
The ones that have come up in the past are obviously less likely to come up but don't rule them out in case they tie into other characters and themes. Also, main characters such as Scrooge and Eddie have themes within the characters that are not main themes running through the book and could be asked in the exam. Context questions can be asked as well so definitely have a good knowledge of background/context as you should always include it in the long questions no matter what the question. For mice and men last week, I revised a lot on loneliness and friendship came up which tie into each other so I was just lucky. Try to get a brief knowledge of everything but a lot of them link together. I'm going to focus on beatrice and justice/law and women/femininity for AVFTB and Scrooge, Ghosts, transformation and guilt/blame. Learning these should give me a good base for whatever comes up. Hope this helps! Good luck!