Are novels good type for that purpose?
The best book is one you will actually read. Your English won't improve by looking guiltily at that tome gathering dust on your nightstand because it's a slog to get through. So yes, novels (in your favorite genre) are excellent for that purpose.
Academic English isn't that different from regular English. Once you have a firm command of English, picking up the academic style is just a matter of reading a few papers in your area.
I found that Academic articles are the best option to choose. They are written differently from other types and - in particular if you pick articles from your field - you will end up with a terminological collection that might be helpful for you in writing your paper. This is based on my personal experience,,