Britain faces wind and rain as summer heat is booted out by weather systems barrelling in ‘one after the other’. Temperatures will nosedive 10C as the jet stream dives southwards, throwing open the gates to the Atlantic. A major meteorological shift will abruptly swap the hot spell for a regime of ‘chopping and changing’. Unsettled weather is forecast into the start of July as Britons are urged to make the most of lingering sun where they see it. Met Office meteorologist Alex Deakin said: “We are in for a shift. “By Friday we are all in the cooler air and some areas are going to be 9C or 10C l…