One word: Vauxhall.
But it's more complicated than that. All of our economy is now so closely bound to Europe, and most of Europe is closely bound into a free tariff agreement, that any deal will be a disaster for both sides.
For instance, Vauxhall, Toyota, Honda make cars here. Parts can be sourced from just about anywhere in the EU, and cars sold anywhere too. How do you get out of that mess? Subsidise car manufacturers, so they can pass on any tariff increases to uk consumers, or reduce prices for exports, but then pass on larger dividends to shareholders and over reward senior management?
The same is true of Airbus and plenty if other real industries. But what about the finance markets, what Thatcher described as those clever people who just make money? Their industry is a house of cards, readily moved elsewhere in the EU. Why would they wish otherwise.
So what does that leave the UK? A problem with open borders in Ireland and between Scotland and England. A pile of heavily subsidised farmers. James Dyson, who happily shifted production abroad. Anything else?