Britain left the European bloc's vast single market for people, goods and services, completing the biggest single economic change the country has experienced since World War II. (AP Photo/Michel Spingler)LONDON – Some businesses said Friday that costs and paperwork are hampering trade between Britain and the European Union as the reality of the U.K.’s post-Brexit trading relationship with the bloc takes hold. A trade deal that took effect Jan. 1 allows Britain and the EU to trade in goods without quotas or tariffs. But that is a far cry from the seamless, hassle-free trade the U.K. enjoyed while it was part of the EU's single market. “We have always been clear there would be changes now that we are out of the customs union and single market, so full compliance with the new rules is vital to avoid disruption,” he said.