So you wouldn't want another say on the basis of the negotiations then? What if the settlement includes remaining a member of the common market but still includes free movement for which the UK may have to pay a hefty fee ala Norway, for example? There are so many different options now, none of...
Once they have negotiated the divorce settlement, they should have another one definitely. Switzerland seem to have one whenever a major change in it's dealings with the EU are in the offing, so the UK should too.