To be correct
We have not yet told them we are leaving - so EU rules still apply
Once we do there if a 2 year negotiation period - EU rules still apply
After 2 years we're out - if there is no finalised deal we're back to WTO rules BUT there may be certain grandfather rights with individual states (as there are apparently on fishing). Effectively we'd be rewinding the clock to the early 80's with the original EU members . God knows where we'd stand with later joiners such as Spain & Romania
Better ask Boris & Farage.............