Here in Sydney in the summer if you don't want to give your cocker a full shave and clip ( which I don't) the groomers shave the tummy leaving all the coat and feathering, so the cocker looks fully coated and pretty. Apparently dogs cool down by pressing their tummy on a cool surface, and if the tummy is shaved all the cooler.
In summer here Flo spends her time when in the house in the rooms which are aircondioned or in the bathroom lying tummy spread out on the tiles. Mind you we are looking 30- 40degree days in summer not a lovely 28degrees that I see London had today, we had 28 last week in autumn and Flo didn't seem at all in difficultly, and the aircondioning only goes on if it's over 32 in our house. We don't change her bed from season to season, she seems to be able to find how to make herself comfortable, even by pushing cushions of the leather sofa so it's cooler for her.