I think you're massively over-estimating the public interest. Even the EU wasn't exactly of interest until the referendum, and even that was only driven by the relatively small UKIP brigade using it as a scapegoat, most of the population couldn't care less about the minutiae of international trade and relations. Most people will only be aware of these deals when they catch mention of it on the news or in the social media feeds, there really isn't any interest in scrutinising it at all amongst the wider population
Direct democracy works when you have a small, well engaged population. The UK does not have that
I think we probably don't inform the public on such issues as much as we should. If such deals could be distilled into an executive summary with some key bullet points with a copy widly distributed, I think more people would engage.