22. Where a supplier of appliances intends to withdraw from the pharmaceutical list in respect of particular premises, he shall notify the Primary Care Trust of this—
(a)at least three months in advance of that date; or
(b)in the case of a supplier of appliances in respect of whom a condition is imposed by virtue of regulation 13(2)(a) as regards those premises, at least six months in advance of that date,
unless it is impracticable for him to do so in which case he shall notify the Primary Care Trust as soon as it is practicable for him to do so.