In principle, yes, a very good idea. Two snags, one temporary, one permanent:
1. Trump has declared his aim to stop free trade, and the UK is no exception to his malarkey.
2. Unlike Europe, the USA is not exactly on our doorstep, so the trade in perishables (and therefore the hit to our farmers) - while by no means impossible, would be much more difficult. Add to that the "just in time" aspect of manufacturing - e.g. motors - and you begin to see that even the USA, despite our frienddhip, is only a second best to Europe.