UK has to thread slowly and get the best deal possible from the EU first.
The EU has already given its ultimatum in clear English: no free movement of people, no free trade. Take it or leave it. Without the free movement of people, the UK might get something like Canada's deal.
And if the EU was all that bad, why's the UK sticking around?
Stop procrastinating, bite the bullet, and cut the umbilical cord.
Think of all the money the UK will save in payments to the EU.