Update

Work has stopped because of legal issues, who is responsible if someone gets hurt. The site owners have arranged a risk assessment but not until June, we mentioned our concerns re public liability, questions -
Is it our responsibility to take out public liability or theirs?

Is there a regulation or law re public liability?

If our responsibility, who to approach for a quote?

We are still working on a constitution for the group.

Any comments or advice along these lines is welcome