Selling, exporting, is all about competitive advantage.
What Brexit simply does is it imposes upon all British exporters a huge, often insurmountable competitive disadvantage.
There are no two ways about it.
Yet there's no shortage of continental cheeses and wine in our supermarkets and that's because we have open borders for goods from the continent. The controls on our side of the Channel are not there and won't fully be in place until March next year, that's a fat fool promise so take of it as you will. But we were supposed to have 50,000 customs officers in place for the beginning of the year! But of course we haven't, all so Johnson could proclaim Brexit done in December last year.
The UK must be a smugglers paradise right now.