This trope is trotted out frequently by those who wish to leave - please could you explain how, exactly, it has held up negotiations or stopped us “getting a deal”?
Those negotiating are, pretty much to a man and woman, supporters of Brexit not Remainers. The negotiations have been held up because Mrs May has ruled out EEA or EFTA membership but her “Chequers” proposal is not acceptable to the EU as they feel that it is cherry picking the single market and puts regulatory functions that should stay within the EU in the hands of a 3rd nation.
Brexiteers want only a free trade agreement - but that necessitates checks on the Irish border which is not acceptable to the Irish (and by dint of veto not acceptable to the EU). In fact May has ruled an FTA out as “worse than no deal” because of the Irish border backstop position (which, need I remind you was agreed by David Davis).
Neither Boris, nor the ERG have actually managed to come up with a detailed, workable, plan - just a lot of vague hand waving. The ERG in particular has revealed itself to be as mad as a box of frogs.
As to a further referendum - much as I would like the opportunity to re-run the question I think it would be unwise. I will never accept that the campaigns were honest or competent and Cameron managed to turn an advisory vote into a binding one (but in doing so left us with “first past the post” which was a woefully low bar for the degree of far reaching change that Brexit will involve) but I have no reason to believe the vote itself was irregular.
More to the point a further plebiscite is fraught with difficulty - what will the question be, include a remain option or not and if you thought the campaign for the first one was bad I expect that a further campaign will be worse. It is also difficult (but not impossible, especially if the A50 negotiations are suspended to allow it to take place) to find time to squeeze one in before next March.
And what of the result - what result could possibly come from it which will do anything other than stoke the divisions which have resulted from the vote in 2016.
Personally, despite being a remainer I have swung again to the view that the only way forward is, in fact, a fully fledged “hard” Brexit, out next March whatever the state of planning and preparedness. Only then will we see, unambiguously, what Brexit means. It might be a great success - in which case I will be very happy to be wrong - but I suspect it will be an unmitigated disaster. At which point we stand a chance that the lies of the Leave campaign will be laid bare to those who believed and voted for nirvana but got samsara.
Mind you that is a dark path - political disruption just for the sake of it, is a dangerous and unpredictable tool.