Private antenatal care but delivery in govt hospital

Hi, is there anyone here seeing a private gynae for their monthly scans but instead of engaging their private gynae for delivery went to deliver at govt hospital? I'm thinking of doing this as my private gynae delivery charges and as well as the private hospitals charges he's delivering at, are quite high. But I'm not sure how to go about it? Do I walk in the I govt hospital for delivery? Or do I at need to book a gynae at govt hospital?