@James2483 Its unlikely that any info will be on Airbnb as they can't know all the various lockdown rules in every country let alone every town.
The Government rules for Bath, I believe, are no more than 2 households can meet inside at any one time. Quite who is breaking the law in the case you describe is less clear to me. I think its the guests not the host but I could be wrong especially is the host would be facilitating law breaking.