Good job on the shed, it's gone up in double quick time. If you want some more information on insulating a shed have a look over on UKWorkshop. Shed builds come up fairly often and the question of insulation must have come up dozens of times. The other problem that comes up often with sheds is condensation on tools, people have come up with some ingenious ideas for ways to stop things going rusty but the best option seems to pretty much always be ventilation.