A further issue is that quite a few countries outside the EU have a free trade agreement with the EU. South Korea for instance. UK will have to negotiate all these things themselves now. Furthermore, the EU is in an advanced stage of negotiating a free trade agreement with the US. Next to the years of setback the UK will suffer negotiating this outside the EU, such an agreement negotiated as a whole of countries is always going to be more favourable then on your own, meaning the UK will have less pressure to negotiate conditions to protect their economy.
It might not be inconceivable that Haas F1 moves its UK headquarters/factory to the mainland once the EU-US free trade agreement is done.