(1) Where an adopting parent takes leave under section 42 he or she shall be entitled, if he or she so requests, to additional adoptive leave for a period of 4 weeks.

(2) The adopting parent shall commence a period of leave referred to in subsection (1) immediately upon the expiration of the period of adoptive leave under section 42 and shall cause his or her employer to be notified in writing of his or her intention to take such leave -

(a) at the same time as the notification of his or her intention to take leave under section 42(2) is given, or

(b) not later than 4 weeks before the date on which he or she intends to take the leave,

whichever is the later.