Britain’s attempt this week to lay out a plan for it to leave the European Union on March 29, 2019, didn’t go smoothly. Ahead of the release on Thursday of a white paper detailing Britain’s Brexit agenda, two of Theresa May’s ministers quit, threatening the survival of her government. Then, a visiting Donald Trump all but killed Britain’s hopes for a trade deal with the U.S. In an interview with The Sun newspaper, he said, “If they do a deal like that, we would be dealing with the European Union instead of dealing with the U.K., so it will probably kill the deal.” (On Friday, Trump then contradicted himself during a press conference with May, where he said the two countries could work out a “great” trade deal following Brexit.) Britain has proposed a “free trade area” for goods that would avoid customs and regulatory checks at the border; a “common rule book” for agricultural and other goods; the phased introduction of a “facilitated customs arrangement” to avoid customs checks; and “reciprocal commitments”…