Activate the console on singleplayer by : pressing ctrl and ` then type in the box cheatmenu.
This will give you a bunch of goodies , From instant winning the castle and instant seige equip building. You can find some cheat menu options in Camp mode, and when your in castle menu.
There is a cheat in Camp mode that allows you to open up and inventory box which has all the items in the game.
Enjoy.