No, the EU will still negotiate and conclude a trade agreement with the UK. However, the pound has just plummeted and is not going to be worth as much, therefore, the UK will be much poorer and unable to afford as many products from the EU and import them. Therefore, your imports are lower. Therefore, the leverage the UK had about imports is no longer even that much relevant anymore.

What the guy below and above said as well : The EU is a massive trading bloc, bigger the the markets of China and USA, or at least comparatively similar. It has it's own strict regulations. If you wish to trade with it, you will abide by the rules made by the EU for its own market, otherwise your products will be rejected as non-compliant. In addition to the very disbalanced trade power of both blocs, the UK is in a particular vulnerable position right now. Without a good conclusion of these negotiations, the UK won't have any other trading partner as it needs to renegotiate everything.

Really, everything you have been led to believe about the UK having the power to conclude its own trades is misleading. The reason why the other 27 member states have transferred competences on common commercial policy to the EU is because it's able to negotiate very very preferential trade deals, and have EU regulations as a common standard for the whole internal market (without having to follow standards in other markets). The UK is going to experience this very fact soon enough, and it's not going to be pretty.