A quick tip. If the cabin is really hot when your boarding don't start fanning yourself or ask if the heating can be turned down until you take off. I was sitting in Finnair's A350 at Heathrow earlier this year and it was so hot I started to fan myself. The FA came over to me and asked if I was feeling well. I said yes it was just a little too warm. She stared at me with a concerned face and went to ask a colleague for a second opinion if I was fit to travel. You don't need these sort of surprises however well meant.