AHC WI A deal between Britain and Napoleon

Could a British government have agreed that France would be left alone, perhaps with some territories left alone by the French Conquerer?

If so how long does the Bonaparte regime survive?

They had one: the peace of Amiens. It... didn't last long. Both countries started breaking it before the ink was dry.

But no. Napoleon by himself is inherently disturbing the balance of power in Europe from the English point of view. Wellington pointed out he thought Napoleon was worth 40,000 soldiers on the field if he was present at a battle. That gives you numerical superiority against nearly any opponent of the day. It makes France the supreme arbiter of the continent.

If the Third Coalition had not arisen, Napoleon would have been seen as a troublemaker, a jumped-up country bumpkin, and a very good general who also had the devil's luck (slipping past the British to go to Egypt, slipping past them to get out and having Desaix come in the nick of time at Marengo). But he had to follow it up with Austerlitz, Iena-Auerstedt and Friedland. At this point, not only was he controlling both Belgium and the Netherlands but he had beaten black and blue every army of note on the continent and fundamentally altered the balance of power. There was no putting the genie back in the bottle after he crippled Prussia and allied with Russia. The British would have rather died than letting him set himself up as the continental hegemon.

So, the window of opportunity for a lasting deal is between 1801 and 1803. Both countries must honor their agreements to the letter and, if possible, make no sudden move towards getting crowned as Emperor, inviting Provence, Artois, Enghien and the rest to come back into the country so long as they agree not to claim the throne and show an interest in gradually letting France's conquests go. Anything less is not going to convince Britain. But that much is already too much for the French and Napoleon to accept.

There were various attempts at peace negotiations during the Napoleonic Wars, but they continually broke down. The most serious one was probably in 1806 under the Grenville government. The two sides could not come to agreement on Sicily, and then Charles Fox, the most pro-French member of the British government, died. If he'd lived on, perhaps some deal (at least a temporary, Amiens-style one) could have been reached?

There were also a few proposals in 1813-14 of letting Napoleon keep his throne in return for giving up all his conquests, but it's not certain how sincere they were, or if all of the Coalition would agree.