LONDON—Exports from Britain to the European Union fell by 68 percent in January as trade was disrupted after the end of a transition period following Britain’s departure from the European Union, according to a trade body representing hauliers. The government did not confirm the data and said disruption at the border had been minimal since Britain completed its journey out of the EU’s orbit at the of 2020 following an agreement on trading arrangements. Since the start of the year, businesses and hauliers have had to adapt to new trading arrangements, including new systems for companies and officials in the British province of Northern Ireland. Some businesses have struggled with new customs declarations and health certificates as the coronavirus pandemic also hits firms. International members at the Road Haulage Association (RHA) reported a 68 percent fall in exports in January, the group said on Twitter. “I find it deeply frustrating and …