Peoples' vote?

Several thousand people marched through London over the weekend demanding a second referendum - but on what exactly?  In order to have a vote, you have to have something to vote for - or against.  And it seems to me that we haven't,  The closest we've come is the so-called "Chequers Agreement" which clearly is anything but an agreement and in any event has been dismissed out of hand by the EU.  Until we have a definite proposal - wherever it comes from - there is nothing to vote on.