Get ya cheque book ready for all that mylar my friend. A cheaper option is down to wickes and get space blanket loft insulation 150mm (they do buy 1 £14 get 2 free). Do ya loft out with that. If your using a tent don't bother with the mylar at all, the tent will keep the heat in. The aircons are noisey, I put mine on a few pillows to reduce vibration. I have mine in the tent it helps with the cooling as it sucks the tent air in and cools it. Make sure you duct the aircon to the chimney independently from your extractor.