We had a wonderful visit to Whangaroa and the Northland region. The homestay was fantastic - I believe you can rent a portion of the house, or the entire home, depending on the size of your party. We did share the kitchen and public areas with Terry and a guest, but they were wonderful. Great location for starting the hike to St Paul's rock, easy to pop down to the pub / fishing club, and Terry has prepared a wonderful dossier on local activities. The rooms and furnishings were comfortable, clean, and modern, and the home is bright, with 360 degree views of the spectacular scenery of the harbour. We were visiting for the blood moon / blue moon / supermoon, and this property has unparalleled views of the sunset and moonrise. Before the moon comes up, as there is almost no light pollution, one can view the Southern Hemisphere constellations in amazing brightness.
If you are concerned about shared quarters, I would encourage you to just communicate with the owner prior to booking, to allay any concerns, or arrange for full use. But I think that this will be a highlight of your visit to the area, a very special place.