Extinction Rebellion is polite and inclusive. It must take that approach out from London where the contrast with the British establishment’s spite is an even greater asset.
Brexit-delay riots are highly unlikely. If you know why they are being talked up, however, you can address the real agenda.
Some will weigh that party unity and Trump’s base is a path to re-election. Others, however, may decide distance is better for them.
Riots are rare but a sufficient force of impact on a concentrated population can create a riot. And this makes “no deal” riots likely.