There is no question that one of the first issues a republican president and congress will address is a review of trade tariffs.

The proposals set out back in June 2016 by the party clearly state that a quasi-VAT tax/duty will be placed on imports into the US. Whether such a tariff is allowed under WTO rules is debatable, and it may be such a tariff/tax gets bogged down in WTO disputes with other countries like China who have much to lose from such a imposition.

What is clear is that a Trump administration is going to reset the trade laws of the world via this import tax. 

If the tax is structured as a tariff, countries with free trade deals with the US may be able to avoid the imposition on their goods imported into the US. If it is in fact a tax (and to avoid WTO rules), it seems likely a free trade deal wouldn't help. But in any country agreeing a new free trade deal with the US, I would expect the Trump tax to be catered for via specific mechanics to soften the blow.

Trump has an affinity to the UK and in a post-Brexit world, the UK could be the first country to benefit from the new world order created by Trump's "America First" policy. 

The UK couldn't negotiate such an arrangement within the EU so this could be a small silver lining of Brexit.

There is much water to flow under the bridge yet, but within weeks we should have a clearer understanding of how the republican proposals on import taxes will work.