Good heavens no, the little incubator you have runs on very low power, a few pence per day I should think, and the brooder was only a 60 watt bulb even if it is the sort that gives out heat as well as light. I would estimate £5 tops for them both over the time you have used them. You will have to look into the electricity bill but you couldn't possibly have used £250 in the time you have been raising them.
Shed looks very cosy, I'm sure they will appreciate the extra space.