(1) An appeal under regulation 43 is to be made to the tribunal before -
(a) the end of the period of 30 days beginning with the date of the document notifying the decision to which the appeal relates, or
(b) if later, the end of the relevant period (within the meaning of regulation 43C).
(2) But that is subject to paragraphs (3) to (5).
(3) In a case where the Commissioners are required to undertake a review under regulation 43B -
(a) an appeal may not be made until the conclusion date, and
(b) any appeal is to be made within the period of 30 days beginning with the conclusion date.
(4) In a case where the Commissioners are requested to undertake a review in accordance with regulation 43D [Regulation 43D was inserted by S.I. 2009/56.] -
(a) an appeal may not be made -
(i) unless the Commissioners have notified P as to whether or not a review will be undertaken, and
(ii) if the Commissioners have notified P that a review will be undertaken, until the conclusion date;
(b) any appea