As I mentioned I have little grasp of politics, so pardon my ignorance if my comments are out of term, but normally any organisation has procedures and policies in place for circumstances where an individual or affiliated party wishes to leave. It seems to me that whilst the basics are covered (have a vote, if its in favour of leaving the EU then submit A50 and leave two years later), but there doesn't seem to be any other "clauses". I remember at the time both those in the remain camp and leave camp had no real factual "this and that will happen" it was all speculative.
For me, regardless of what the terms and conditions of leaving are, the country voted, the vote was to leave, A50 was submitted and so we should have left at the end of March. If any deal could not be agreed in those two years after A50 submission then that was the fault of the government and their nominated representatives.