It shall be the duty of the Authority to prepare and publish a document containing its guidance as to the manner in which persons authorised to enter premises under subsection (1) of section 19 should—
exercise the power conferred by that subsection; and
conduct themselves after entering premises in exercise of that power.
The Authority may from time to time revise the guidance published under this section; and, if it does so, it shall publish the revised guidance.
A requirement under this section for the Authority to publish guidance or revised guidance shall be a requirement to publish it in such manner as appears to the Authority appropriate for bringing it to the attention of persons likely to be affected by it.