I follow British politics pretty closely - I'm a citizen! - but I've never quite managed to understand the whole Brexit thing. I'd guess the net result for Britain in practice would be that all of the mostly bad stuff of being in the EU would remain, while all the mostly good stuff (no visa needed to go to Spain!) would go away. Whatever the merits of the EU as a project as a whole, there are some good things, and all the anti-EU stuff seems to be channeled into stopping the good stuff. How the world works these days, I guess.
I saw Boris in a theatre in London once. Stephen Fry was there too! With his ill-fitting suit and backpack and bicycle helmet (he genuinely does ride his bike, but his costume is still a pose) he really did look like a character from the Upper Class Twit of the Year.