Brexit was never about trade deals. It was about racism, pure and simple, with an enormous dollop of bogus nostalgia thrown in for good measure. Brexit was based on simple-minded lies and pathetic soundbites, swallowed whole by ignorant foolish people who wanted to return to the "glory days" of Empire and Spitfires flying over the White Cliffs of Dover. Slimy creeps like fat Boris papered over this unpleasant reality by pretending the UK was being "held back" by the EU but that was just another of his infantile lies. If the EU constrains trade, how is it that Germany (at the heart of the EU) is one of the world's most successful exporting nations? Meanwhile the Commonwealth has always been a sick joke, its purpose primarily to give E2 a photo op every few years. It's full of dictators, tyrants, and other unsavory types, and even the decent nations are too far away for most trade to be practicable. And even if trade with the Commonwealth were possible, it would not make up for the massive loss in trade to the EU.
The fact is that Brexit was always a stupid idea, and only very stupid and ignorant people voted for it. Now, they deserve everything that is coming to them. Sadly, Brexit has wrecked the lives of young people who deserved much better. But hey, that's populism for you!