This is going to be an interesting divorce that's for sure.
UK has become embedded so deeply into EU regulations it's not easy to see the wood from the trees. So many many anomalies to resolve.
Take the Northern Ireland who has 50% of his farm in NI and 50% in Ireland. Will there be a border control. How will he be able to grow produce in one place and transport to another.
What about UK assembly plants using parts from within the EU and selling back the finished product. Will non-EU tariffs be due on parts as they left EU or when the fully assmbled finished product leaves the UK?
Fishing rights is another.
The start of the divorce is known as is the legal end date.
The in-between shenanigans and UK future isn't known by anyone.....