How will Brexit affect International trade for the UK?Watch
First of all I made it clear that no one has every left the EU before: it's impossible to understand clearly the effects of Brexit on the economy. Also, it hugely depends on a hard/soft Brexit? ie are we planing to leave the single market etc.
Then include pros and cons;
May lead to higher important tariffs - increases costs for firms within the UK. Leading to cost push inflation, lower profits, fall in choice, fall in consumer welfare etc. Try and refer to Micro (producer/consumer) and Macro (whole economy)
any more info just message!
To start you off, look up some of the papers based on gravity models (the notion that bilateral trade is most often dominated by economic size and geographical proximity) that were done pre-referendum and evaluate their applicability in certain terms of Brexit.