I've added orientation to the diagram. Unobstructed sun from North-East to about North-West, then the large tree you can see in the picture behind the glasshouse shades the last of the sun as it sets. It's the southern hemisphere so the sun heads East>North>West. The photo of inside the glasshouse shows you the shadows at about 10am, I reckon its getting about 6-7 hours of direct sunlight per day at the moment in early spring.
I've only just moved down here to Dunedin so I can't tell you first hand what the seasonal variation in temperature is. Wikipedia climate data below. As you can see, even in the height of summer the temperature is still quite low, hence I'm thankful to have the glasshouse.