Lines of cars snake from gasoline stations. Fights break out among angry motorists trying to get fuel. Grocery staples are out of stock on store shelves. A charity warns that doubling heating bills will force a million households to rely on extra blankets to stay warm.

This was supposed to be the year the U.K. broke free of the European Union and forged ahead as a buccaneering free trader, delivering the benefits of a new, confident "Global Britain” to workers and companies at home. Instead, that picture of Brexit utopia is looking more like a dystopia.

As Prime Minister Boris Johnson’s Conservative Party gathers at its annual conference this week, the promise of self-determination has given way to a foreboding sense of economic isolation.