If you want a doctor to visit you at home, you have to ask for a home visit. You're supposed to do that before 10:30 in the morning, but obviously, if it's an emergency, you can phone at any time, night or day. It might not be your doctor that comes, though. It's quite often one of the other doctors in the practice. It doesn't really seem to make much difference.
Otherwise you make an appointment to see your doctor at the health center. You usually get seen the same day. Not always of course, but ususally, as I say. They hold surgeries between 9:00 and 11:00 every weekday, and from 4:00 to 6:30 Monday to Thursday. Saturdays are only for emergencies.