A Temporary Event Notice (TEN) is required if the hirer intends to sell alcohol during their booking. It is the legal duty of the hirer to obtain the notice from Bath & North East Somerset Council - https://beta.bathnes.gov.uk/temporary-event-notice-ten but you must inform the hall by ticking the TEN box in the “Facilities Required” section as a limited number of notices are allowed per year at any one venue.
Please note that a TEN is not required for regulated entertainment as the hall has a permanent license for this.