So yes, you need AC. Many people have it built in, with air being pumped through air ducts that are hidden in the walls. (They also pump the heat out in the winter and it's called "central air".) If you don't have it built in, you can buy window units and attach them firmly onto the outside of the window. That makes for some interesting dog walks in our neighborhood as some of those units are four floors high and look a bit "loose" to say the least. They also drip water which can be a shock when it hits you on the back of the neck as you pass by.
You don't walk under anything that looks like this.
But what's all this fuss from my friends and family across the Pond? It can't be that hot, surely? It's England for crying out loud. Wait a minute! It's actually hotter than Chicago at the moment, and I'm moving to a house with no AC? "Nooooooo," she says, in her best American accent. And I've heard that all the portable air conditioning units have already disappeared off the shelves. God forbid that B&Q anticipate a growing trend and actually have some in stock.
Actually, I'm more worried about the whining that will ensure from American husband and American-raised son. The things is with Americans in England, if you open all the windows they have a fit because there are no screens to keep the dastardly FLIES out. You know, those flesh-eating beasts that will surely bring death and destruction? You should see the Ball & Chain if one gets into the house. So trying to get a cool "cross breeze" through a hot house will be a battle if there are flies and bees in the near vicinity.
The long term forecast is predicting that this current heat wave will have abated by the end of June, so here's hoping. England, you're on a promise.