Once the tenant's notice or a copy of it has been given in accordance with section 42 or Part I of Schedule 11—
to the landlord for the purposes of this Chapter, or
to any other landlord (as defined by section 40(4)),
that landlord and any person authorised to act on his behalf shall have a right of access to the flat to which the notice relates for the purpose of enabling that landlord to obtain, in connection with the notice, a valuation of his interest in the flat.
That right shall be exercisable at any reasonable time and on giving not less than 3 days' notice to the tenant.