If the Brits won't extradite him, let them try him and let them have to deal with the "release Osama" hostage takers. No reason we would have to do so.
Better still, of course, is to shoot him while escaping. A couple shots to the guts, then benign neglect as he slowly bleeds to death.
Done correctly, execution by gut-shooting does not result in death by hemorrhage.
Death comes, at the end of an protracted period of agony, of peritonitis.