SPOILERS FOLLOW


Actually, there shouldn't be as much fighting as in TTT.

There will be a battle near Gondor (in which there are quite a few casualties, including some known characters),

Frodo, Sam and Gollum will be in a small battle against a monster and then there will be another small battle at the mountain of fire near the end.

That's all the fighting I remember from the books and one of those fights comes from the TTT book.