Unfortunately that's a proposal that involves unicorns and fairy dust - the EU rules are that you drop out of the EU on the second anniversary of triggering A50, deal or no deal. Moreover there is no legal mechanism within the EU treaties to rescind A50 once it's been triggered.
All this 'meaningfull vote' stuff is just the witterings of people who haven't read the rules, and ammusingly such witterings do nothing but play into hands of the hardest or hardest Brexiteers. To reject whatever deal May gets ensures that the UK will leave the EU on 1st April 2019 with no deal in place on pretty much anything.
You'd have thought that people who are so keen on the EU might have taken the time to read the EU's rules, but apparently not...