Keeping a shed warm in winter and cool in summer
I have a similar shed ( 12 X 8 US ft.), I have mineral wool insulation with OSB ( cheap imitation plywood ) over it. It also has an 8 X 4 ft glass skylight. I have aquariums in it and put plants in it in very cold weather. I am impressed by how comfortable the temperatures are. It has about 600 watts of aquarium heaters  and lights ( they cycle off/on). I use a 8 in. diameter fan in the one window when hot. Moisture has not been a problem; no moisture barrier. I have aluminum ( aluminium ) along bottom edge of the skylight and condensation does drip from it. Our lowest temperature is 15 F , typically 32 F, 0 C , at night in winter.