I don't claim 20-20 hindsight, and certainly far less than that when predicting the future, but this dream of all sorts of beneficial deals with the rest of the world seems very unlikely to me. Some runes people might like to consider are things like these Financial Times articles of October 5, 2017:

* Trump opposes EU-UK agri-deal in blow to Brexit plans
* Tariffs and energetic protection of US trade is the American way

(The second article makes the point that it is not just Trump who thinks this way)

The Financial Times runs a paywall scheme, so I can't simply link to the articles, but the titles are clear enough, and if you are interested enough I am sure you can find a physical copy or join for a modest fee.

Back in July when Trump said he saw a great trade deal with Britain, he did not necessarily mean we would like it.