What options remain?
In a “soft Brexit” plan, the U.K. could stay in the EU customs union. It’s unlikely, though, that May will agree to that, because it would involve accepting EU regulations and court jurisdiction and restrict Britain’s ability to negotiate trade deals with other countries. The more likely outcome is some version of the “hard Brexit” scenario, in which the U.K. would establish a free trade agreement with the EU (like the one the EU has with Canada), so there would be no tariffs. The U.K. would set its own regulations and immigration and trade policy. The U.K. and EU would have to institute customs and regulatory checks at borders. To circumvent the Northern Ireland border problem, May hopes that checkpoints there can be avoided through some high-tech scanning technology yet to be invented.