We haven't had correct information since B4 this idea was muted by Churchill. He wanted peace across Europe but none of the MPs of the time did. By the time it was decided that the UK might benefit, the original entrance plans for joining had moved on, France and Germany had closed ranks and for some reason, the UK played by their rules

. Which meant that all along we've had little chance of debating issues or saying 'no' if it wasn't in our best interests

Ted Heath pushed it forwards and apparently, the Referendum then to go into the Common Market was a 'yes' vote. But most of the entrance had been agreed.
Now we are in a bigger mess than B4 but we should not get another Vote. Otherwise it will go on and on until it becomes what others actually want and that isn't Democracy. What we should be able to have is access to read the 'deal', DH got it up earlier and even as a Researcher used to reading between the lines, couldn't get a grip - all the Clauses and b, c, d etc. means it needs a team of lawyers to interpret it.
It will be what it turns out to be. No one can predict if the UK will be/not better off. We haven't got there yet. We can't know if we would have been better staying out completely.
What bothers me is the UK being held to ransom over good food stuffs and medication accessibility, however, I haven't seen NICE or the Health Minister making front line news about that possibility!