A mum has issued a heatwave warning to parents after her daughter ended up in hospital with a 40 degree temperature after a day at the beach.Charlotte Finch, 30, was out with two-year-old Evie and sons Teddy, three, and Harvey, 12, on June 24 when temperatures were up to 28 degrees.The full-time mum said the kids were covered up, were continually slathered in sunscreen, had hats to cover their heads and were kept hydrated throughout the day."I had followed all the guidelines, and the children