x-post Jassy. I agree people in the UK could be more sensible re. hats, suncream and staying in the shade/indoors during the hottest part of the day, BUT I do think people go out because with the breeze, it's nicer than being stuck in a stuffy house with no air conditioning!
I'm absolutely not arguing that Australia is better set up to deal with heat than Australia, particularly when it comes to the provision of public shade and cool public places in general. Though I never lived in a house in Australia that had aircon. My parents now have it in two rooms, as does one of my brothers, but it's definitely still not 'standard' in homes - even high end homes - jurging by some of the online real estate I've been browsing!
As a point of comparison - humidity in London today is hovering around the 45-50% mark. Due to drop back to 30-odd this afternoon Likely to go a bit higher later in the week with lower temps, but not much.
Average summer afternoon humidity in Brisbane and Sydney sits around 60-65%. Both are humid subtropical climates. Going outside in Brisbane in summer when the humidity hits over 70% (often) is like swimming.
Brisbane today is 23 degrees with 88% humidity and no precipitation risk. In winter.
It's not Singapore, or places like that. But it definitely can't be described as a very dry heat (which, having spent plenty of time in western Qld and NSW, is very enjoyable. Give me 38 degrees there any day over 28 in Brisbane.)