At referendum Vote for leave gave no explicit notion that what type of Brexit voters wanted to look like.
The idea of Dr Douglas Bamford (at Oxford) is very appealing that there should be a final referendum on.
The government has negotiated the best possible deal with EU, this should be put to the voters with three options
The government should not announce a referendum in advance. It would be a terrible idea for the government to announce this in advance.
If the EU knew there would be another referendum then they would lose any slight incentive they currently have to offer a half-decent deal to the UK. From the EU perspective offering a bad deal increases the chances that remain will win a referendum.