The WTO provides a loose foundation for trade without agreements, and guidance on how agreements can be reached. Trade without agreements is subject to tariffs

The WTO provides a loose foundation for trade without agreements, and guidance on how agreements can be reached. Trade without agreements is subject to tariffs and major restrictions severe enough to cause serious economic damage. Agreeing FTAs can take years, hence the need for a transition period until one is agreed between UK & EU. What May did was entirely consistent with trying to achieve the Brexit that was voted for.