18.—(1) Subject to subsections (2) and (3), no provision of any lease, tenancy agreement, contract or other agreement (whether entered into before, on or after the commencement of this Part) may operate to vary, modify or restrict in any way section 12 or 16.

(2) Subsection (1) does not prevent more favourable terms for the tenant than those that apply by virtue of section 12 being provided for in the lease or tenancy agreement concerned.

(3) Obligations additional to those specified in section 16 may be imposed on the tenant by the lease or tenancy agreement concerned but only if those obligations are consistent with this Act.