AIBU to think that just because other countries get hotter than Britain, does not mean being here during heatwaves is lovely and fun? We don't have the infrastructure for heat - see the trains going slowly to prevent buckling, total lack of air conditioning in most homes - and we aren't 'culturally' prepared for it - look at all the threads about schools who expect children to be out for significant lengths of time during the hottest parts of the day.
I grew up somewhere with average summer temps of 105 degrees - and it was fine because the infrastructure was there and everyone knew how to keep themselves cool.
So basically, AIBU to think that it doesn't matter that other places are also hot, it's hot here now and it's bloody annoying and getting in the way of normal life!