Thank you all for your input. Really apreciate it. This week has seen a temperature drop already, over night is down to 10, makes me suspect its gonna be a cold winter.
We will use a heater- thats for sure but it only takes the edge off and tends to dry out the air making it uncomfortable. I think we'll dress baby warm- a singlet, her mokapuna and pjs over that if she needs, inside her sleeping bag and a blanket on top. She will have gloves on too if needed, maybe over kill but DS1 use to get such cold hands and we can get a range of materials from cotton to wooly 1s