Parliament don't need legislation for the right to vote on the deal, they already have it, by way of a threat of a vote of no confidence in the government at any stage, forcing a return to negotiations for a better Brexit deal in exchange for dropping the no confidence vote motion.
Or they can actually stage a vote of no confidence once more details of the deal are known - but this risks winning! If the europhiles and remainers were unlucky enough to won, this would mean a new leader and possibly a different party getting in, and I'm pretty sure nobody wants May's job right now.
So all this unending parliamentary fuss is just posturing to ensure that all involved can look innocent once the dust has settled and all can say they did great things to get a good deal. But not at the risk of actually having to take responsibility from the muggins Theresa May who's stuck with it now.
Remember that politicians don't live on oxygen, they live on power. And absolute power without responsibility is the ultimate goal.
