"Also, Tories have commons majority and I am quite sure that, if MP vote is after all required ... Brexit vote be pushed through no matter what."
I'm not. It's a matter on which the big parties are split and have been for a long time. The whole referendum thing was an attempt to glue the Tory party together. It hasn't worked. I think it's an issue where whips will be defied by MPs who believe that the national interest is at stake.