keeping baby cool

So
I'm in the UK and at the moment we're experiencing a heat wave ☀️ it might not sound hot to other people but it's 27 degrees here and to us that's absolutely fucking boiling!!!!!! I need advice because my little boy who is 9 months old at the end of this month isn't coping overnight with it being so warm. He's going to bed in just a vest, his window open slightly and someone suggested putting ice in a bowl and leaving it in his room which is meant to cool the air. His blinds and curtains are drawn through the day to keep it dark and cool and I feel like I'm doing EVERYTHING but his monitor says it's 25 degrees in his room and when I go in it's red hot. What can I do to cool it down?!?!?! I'm looking at portable AC units but decent ones are about £200 + and I don't have and won't have that kind of money anytime soon. Suggestions please!!!!!!