http://ukandeu.ac.uk/explainers/trade-deals-with-third-countries/
This is a good article on the UK negotiating trade deals with Third Countries and the possible outcomes.
The UK is interested in trade agreements with the US, China, Canada, Australia & New Zealand. The article goes on to say:
"Free trade agreements (FTAs) are associated with increases in bilateral trade: so, while it would obviously depend on the terms of specific deals, it is probable that UK trade deals with third countries would increase UK trade.
However, since tariff rates are already low, there is limited potential for tariff reductions to increase trade flows – tariffs between the US and the EU average about 1.6%.
Non-tariff barriers (NTBs), such as regulatory differences, are much more important. The estimated cost of NTBs on goods is 12.9% to 13.7% between the EU and the US, and on services (which make up 80% of the UK economy), sectors such as business services and financial
services face NTBs worth on average around 30% in trade costs.
There are some simple solutions to reducing these costs, such as through mutual recognition of technical standards and expanded labelling for food products. However, many of these costs reflect regulations arising from differences in preferences. For example, if UK citizens do not wish to have chlorinated chicken or genetically modified food in the country, then there is not much expansion in trade that can be expected without seriously undermining the wishes of the public.
But even the most ambitious set of FTAs is unlikely to replace the trade lost as a result of leaving the EU. For example, the National Institute of Economic and Social Research (NIESR) estimate that concluding FTAs with all of the above countries, and more, would only boost UK total trade by about 5%, while Brexit will reduce it by more than 20%."
