The British Battles website has accounts, maps and orders of battle for dozens of famous battles involving the British army. Included are Battles from King George’s War, the Jacobite Rebellion, The French and Indian War, the American Revolution, the Peninuslar War, and other Napoleonic Era battles. It’s an incredible resource for the miniature wargamer.
The Napnuts site has a set of rules for conducting a Napoleonic Peninsular campaign. The Peninsular Campaign makes for a good campaign because of its relatively limited scope.