The main benefit of trading on WTO terms is that they are known, now.
I am involved in a business that imports glass from the EU, mainly Germany and Spain into the UK. (benefiting from the different standards within the EU, ironically) We also imported from the USA, and exported to the USA and Nigeria, so I understand free trade and tariffs.
For projects that take place in 2021 and beyond, which we are pricing now, we need to include the cost of tariffs, but of course, I don't know what the agreement will be, whether we will have one, etc, etc.
So how can we price things? We assume that we will be on WTO terms, or that any agreement will be better than WTO terms (a fairly safe assumption)
If the project is profitable under WTO terms, then we're fine. If we end up with free trade on construction products, excellent, we can either make extra profits or drop prices.
Either way, the WTO terms mean that we can plan ahead.
@Ally Maxwell have you ever imported or exported anything?