hi Derrick , not insulated mine yet, but was thinking of uses old quilts as when i built it i doulble skinned the walls with the intention of insulating them at a later date.
i Have a halogen heater on the go at the moment but i also have an oil filled heater and a gas fire for when it gets colder, i have venting in the roof. In the summer it also gets hot in the shed so i either open the door and put a fly net up or i use the vent i have at the base of the shed which draws colder air from under the shed with help of an old fan
i,ll put some pics up later for you