The talks of cross party cooperation are just the latest attempt by the pro remain MPs to try and water down Brexit into pretty much a BINO and call it a 'compromise'. There is no compromise to be had - hence why we had to have a winner take all referendum - Leave and Remain are 2 complete opposites - there is no middle ground it's a binary choice in or out. It's impossible to come up with a version of Brexit that will satisfy leave voters and make the remainers happy and neither should it expect it. A large part of the problem is May has tried to deliver a Remain version of Brexit (or should it be a Brexit version of Remain?) which pleases no one as it's the worst of all worlds. Any cross party talks wont make any difference as the issue is most of the MPs including May simply don't want to deliver the Brexit that the people who voted for it are expecting.
All of the Brexit problems can pretty much be bpiled down to the simple fact too many people involved in our political class, civil service, various instritutions who needed to carry out the process of leaving have never accepted the result and have tried everything except delivering on the result properly. May has been trying to pretend to be pro Brexit but her actions have been of someone desperate to remain as much as possible and leave as little as she can get away with.
The main things people voted for were pretty clearly - end of ECJ, end of freedom of movement, out of single market, out of customs union, no annual payments). Those 5 main red lines meant there was only 2 options that would fit with the EU rules and honour the vote - leave straight onto WTO or negotaite an a FTA like Canada, Japan, etc. We were offered that deal about 3 weeks after the referendum but May just conspired to take that off the table and bounce us into her cancerous deal which couldn't have been much worse if she tried.
David Davies was absolutely correct when he insisted on day 1 we must not agree to pay the EU any money or negotiate terms of any withdrawl agreement unless done in parallel with trade talks - as it destroyed our best leverage but May happily over ruled him and capitulated and that was the tone for the whole process.