this is similar to running a cricket club, or scout club
For running a scout association each lesson could technically require an individual risk assessment for every piece of equipment, and lesson. The hall needs to be safe, and you need to prove that it's safe. Also GDPR, and safeguarding, background checks, money laundering.
> hold up to legal scrutiny from an activist court official
Its not the USA. activist court officials require a functioning court system. Plus common law has the concept of reasonable. A moderated forum will be of a much higher standard of moderation than facebook/twitter/tiktok.