It's a real "thing", yes, there are hazards, yes, but I'm going to have be a pain again and point out that context/scale is important when trying to draw comparisons with the French event. From that link..
"During the heat wave, which began in June and continued through mid-August, temperatures soared to 20–30 percent above average. Even nightly temperatures were higher than the average summer midday highs. The heat was particularly severe in France, where the temperature remained around 99 °F (37 °C) for more than a week in August in some areas."
Hopefully parts of the UK might be facing no more than maybe two days, one or two nights of very elevated temperatures.
It was the continuous run of night upon night of very high temperatures that was one of the major factor in the high casualty numbers in France in 2003.