"{ You don't need trade deals to buy things from other countries.}"
Of course you do. So you buy 'cheap' nappies from China that have harmful chemicals used so that babies bums get ulcers etc. It all needs certifying and checking and a legal framework around it. Leaving the EU with no deal rips it all up.
Why is this so hard to understand?
@1tisILeClerc, as someone who spends so much time 'explaining' to people what trade deals are all about it might be helpful to everyone if you actually do some research and realise that you have some fundamental misunderstandings.
Imagine 'Newland' becoming independent and starting out without any trade deals.
Shortly before independence they publish their WTO schedules and join the WTO. Those schedules describe how they will deal with other WTO members, what tariffs they'll charge for imports, and what conditions have to be met to export each commodity to the newly independent Newland.
Straight away businesses based in other WTO member states can sell goods to businesses based in Newland 'on WTO terms' - the terms which Newland has advised the WTO that they will operate. If it's Newlandish law that your Chinese nappies need to pass certain tests before being allowed in the country then that requirement is notified to the WTO.
No trade deals are required because WTO membership itself provides a legal framework for international trade.
Sometime down the line 'Newland' may want access to export its fish to its former colonial power 'Oldland', which usually operates a strict policy of no fish imports. They do a deal with Oldland so that they can export their fish to Oldland's otherwise-closed market and in return they lower the tariffs charged to Oldland's car manufacturers for cars imported into Newland. The agreement's notified to the WTO and both parties continue their original arrangements with other WTO members.
That's your basic (and very simplistic) trade deal. You can see that it's perfectly possible to trade 'on WTO terms' without any trade deals at all, but you can offer (and receive) more beneficial terms if you enter into preferential arrangements with other countries.