Hello. Im Am Currently On Cerelle (Desogestrel) And Have Been

hello. Im am currently on Cerelle (Desogestrel) and have been for two years as contraceptive. I have had irregular light periods throughout. After a recent consultation with my GP i have been prescribed Norehisterone 5mg in order to delay my period for my holiday. I have been told to take 5 days before i go twice a day. I have forgotten whether i was supposed to take it instead of the Cerelle or as well as. I will not be sexually active whilst on holiday as I am going with a friend not partner.