If you want to see how exactly a Westminster Parliament would stop duly elected MPs who did not follow the rules, look at the 2022 controversy about the Parti Québécois MPs who refused to pledge allegiance to the monarch. They were physically stopped by the sergeant-at-arms.

The UK has MPs who won't pledge allegiance. https://en.wikipedia.org/wiki/Sinn_F%C3%A9in -- they're so integral to modern parliamentary procedure that Parliament's own systems just assume they don't count for purposes of working out a majority. If your government can scrape together enough people to get Confidence and Supply unless Sinn Féin MPs turn up, you live another day. Their grand political gesture over decades is worth nothing if they ever sacrifice it to cast a vote and so Parliament's own systems assume that would never happen.

But Binface's garb isn't a political point, being turned away because he's wearing a bin isn't some grand political gesture supported by his voters, it would be pointless so that's why I wouldn't expect him to do it.