As there is another heatwave, I'm just going to list why we suck at handling it so much, for anyone who is curious.
Infrastructure. Building were made with the intention to keep heat in.
The UK is made up of islands. It is surrounded by water, which usually means it's humid, when the temperature rises. When it is humid, the sweat on your body, can't evaporate and stays on your skin. It sort of traps the heat in, instead of cooling you down, like it's meant to and makes you sweat more. Viscous circle
Air con. A lot of places do have air con, like shops and offices. The average home, does not. To buy a singular air con unit for a room, it's about £100-300. Depends on what you can buy. To get a whole house fitted out with air con, can cost around £1000-6000. This is not taking into account how much it cost to run it, with energy prices being so high. It's a luxury that most people will not save up for as the heatwaves are sporadic. If it was the norm to get very hot temperatures throughout the whole of summer, air con would likely be viewed as a necessity and wpuld be a normal part of people's budget
Not enough time to Acclimatise. Heatwaves will only last a couple of weeks at a time, before the weather changes to a more mild temperature. For the majority of the year, the UK (mostly of England and Wales, it is more cold up north) temperature stays about 10-20°c. When a heatwave does come, it is usually about a 10°c jump (at least) from what the weather was the week before. The Heatwave is normally only a couple of weeks, before weather drops again. A lot of the times, storms follow after. It will then be cool again for quiet a few weeks, at a temperature brits are used to, before it suddenly changes again. The heat is hardly ever around long enough for the body to get used to it. If your body does get used to it, the cooler temperature that follows, pretty much reset your resilience to hot temperatures the next time there is a heatwave.
When it gets hot, there tends to be a hosepipe ban. Water companies will call for a hosepipe ban, meaning people will not be able to water their gardens, no sprinklers or paddling pools. The heat often causes ponds to dry up, rivers and lakes to shrink. Probably why there is sometimes a storm after a heatwave, all the evaporated water comes back down when temperatures cool.
It's not normal. The temperatures when the UK is hitting, is not normal. People you see complaining about the heat, did not grow up with temperatures getting this high. They just aren't used to it. Some Brits may be aware that the heat is not normal and may be why they struggle with it so much. It is different when travelling to a hotter climate, as most people travel with the knowledge that where they are going to, is meant to be hot.
So here you go. Hope this was an intresting read for anyone curious
Edit: As this is getting shared I would like to spread the word of putting hot water bottles filled with water, in the freezer. Put that lump of ice in your bed at night and it does cool things down.
Edit 2: As a comment kindly pointed out, if you do use the frozen hot water bottle method, don't reuse it with hot water. Freezing will weaken the rubber and will offer less protection from heat, which could lead to burns.
Additionally, make sure to check the expiry date of the hot water bottle (yes, they do have them). I burnt my stomach before as I used an old hot water bottle.