Have not followed everything on this topic, but if getting back to imperial is just a way of showing ties are cut with the EU, that's just plain stupid. That's putting politics where it doesn't belong, and it's unfortunately a very concerning trend as of late.
The metric system is universally used in science, and as such, there are objective benefits to all use the same system regardless of politics. It won't rob you of your sovereignty - contrary to many other decisions that are currently a lot more concerning sovereignty-wise and that the UK doesn't seem to be very reluctant to.
I can understand why the US still uses imperial (but it's increasingly using both), but for a country that has already made the switch (which has an enormous cost), making the switch back doesn't seem to make sense and would have yet another gigantic cost for no good reason.
But since I kinda like democracy (when it's really democracy), I think if the question in the UK is a real and important one, and not just a stupid tantrum or political maneuver, they should have a referendum. Let the people decide, but giving them all implications, including the cost, beforehand.