Cycling UK's campaigns team has produced an online kit that helps you draft letters to your local council, asking it to create more cycling and walking space on the roads during the Covid-19 restrictions.
https://action.cyclinguk.org/page/59646/action/1?ea.tracking.id=klwnbug
One advantage of using the kit is that it fills in details of the laws and regulations that enable local authorities to do this, so the council can't claim that it's not allowed to or that it would have to wait months for public consultation.
There's a blog post with some background to the campaign here: https://www.cyclinguk.org/blog/why-we-need-more-space-cycling-and-walking-during-lockdown