Part 1 was getting a bit giant and in the miraculous event that I manage to sleep in a little tomorrow, it seems a good idea to start the new thread a little early. Part 1:
www.mumsnet.com/talk/weather/4590238-met-office-red-warning-for-extreme-heat
Met office warnings www.metoffice.gov.uk/weather/warnings-and-advice/uk-warnings
We didn't quite get to record UK temperatures, though lots of site records were achieved and Wales beat its previous record temperature by more than 2c. Tomorrow we look very likely to beat the UK record and to surpass 40c.
Tonight, obviously, do everything you can to cool your homes down, it won't be easy with lows of 24c in some places. One more day and it will feel much better for many.