First came the Brexit trade deal. Now comes the red tape and the institutional nitty gritty. Four days after sealing a free trade agreement with the European Union, the UK government warned businesses to get ready for disruptions and “bumpy moments” when the new rules take effect on Thursday night. Businesses were scrambling Monday to digest the details and implications of the 1,240-page deal sealed by the EU and the U.K. on Christmas Eve. EU ambassadors, meanwhile, gave their unanimous approval Monday to the Brexit trade deal with the UK Germany, which holds the EU presidency, said the decision came during a meeting to assess the Christmas Eve agreement.