If UK wants to trade with EU, UK still has to follow all EU regulations. If UK wants to trade with EU, UK still has to follow EU immigration policies. If they want to avoid those things, they don't get access to the single market, there's no way around that.

If you're so sure the UK will be better off economically, you should put your money where your mouth is and trade against the overwhelming deluge of financial analysts who say the exact opposite. Last I checked the UK banks were down ~30-35% today, sounds like a cheap deal for you.