Hi
If I may add to this topic I have build workshop using aerated blocks and plastered inside. Pretty easy to do it - even for amateur builder like me, especially when you employ your wife to mix a concrete :) . There is great advantage of this. I heat there very occasionally (wood burning stove +blowers), only when I plan to spend there long time there and is very cold outside. Sometimes I don't heat there for weeks. Because of great heat mass and insulation factor of aerated blocks temperature inside never dropped below 5C. There is no problems with damp or condensation. I wouldn't risk to weld, grind and cut in a wooden shed but I can do it in my shed without any worries. Don't remember overhaul cost of material but it was a way cheaper then buy this size(15m2) wooden shed.