@Thande: I think that America will not go to war with Britain in this ATL. In OTL the impressment and trade barriers were some the major causes of the war and with a peace between Britain and France in 1810, presumably American merchants will once again be able to trade with the Continent and the British navy will no longer quite so many sailors. Plus I doub the administration at that time would really want to pick a fight with the full might of the British Empire.
However, we are still left with the northwest territories. here we have to conflicting goals between the British/Native Indians and the Americans/Southeast tribes, The British and their Northwestern Indian allies wanted to create some kind of Indian state in the Northwest, for the British as a buffer between America and Canada, and the Indians for independence. The Americans obviously wanted complete control of the Northwest territory and the Southeastern tribes were old enemies of the tribes of the Ohio valley.
So here, we have a tinderbox. The British supplied guns to the tribes of the Northwestern territory, thereby angering the American settlers, and fueling the feeling among the northwestern Indians that they could in fact stop the Americans. Whether or not the British get involved, the Indians of the area will get in a war with America, probably led by Tecumseh and Tenskwatawa. The question comes down to whether the British will get involved with them, or simply let the Americans and the Tecumseh's Confederacy duke it out. Unfortunately I don't really know enough about early eighteenth century British politics to really know.