I have finished reading Redwall and I feel that this book would make a very good resource for a war game or RPG. In fact there is a Redwall RPG already. The text contains three books, The Wall, The Quest, and The Warrior. Although I feel that the second and third parts of this story are better suited for a war game, I suppose that part one could be worked into a game.
Splintered Light Miniatures offers many fine miniatures of mice and rats, the two main character types in the text, but also offers a host of other animals that were mentioned in the text.
Although a bit smaller than I envision the abbey, the Mini-Art offers a 1/72 Medieval Fortress could be used to complete a scene. Many of the scenes of the siege of the abbey could be set up using this model and Splintered Light Miniatures.