The UK hasn't passed EU laws since Brexit was done Jan 2021 like they did when they were a member. It's just a free trade agreement now. It is up to UK exporters to provide proof of compliance just like Canadian exporters to EU. 42% of total UK exports is to EU, even pre-Brexit it was below 50%.
In 2015 it was still just 44% of total UK exports to EU: https://www.ons.gov.uk/businessindustryandtrade/internationa...