Early termination of fixed term tenancy

Tenancy Types and Management

A tenant wishes to terminate their fixed term tenancy 2 months early. In the template RLA tenancy agreement (May 2019 ed clause B7) , it only refers to the tenant having to pay:
1) reasonable costs for reletting the property - how is this to be determined as agents will take a flat fee i.e. for tenant find service only
2) pay the rent - there is no mention of the tenant paying the other costs eg council tax; water rates; standing elec/gas charges - shouldn't the tenant be liable for these until the end of the contract or until a new tenant is secured.