By Tim Hanlon Brits are set for a “muggy and humid” day wherever you are in the UK with highs of 20C says the Met Office. And the exact time that the mini heatwave is set to hit is from 1pm with temperatures climbing into the high teens and hitting 20C by 4pm in the South East and East of England. It will also be a warm day across the country and in the north of Scotland it could reach 18C. It is the start of a 72-hour African plume with the above average temperatures continuing through Friday and into the start of the weekend before starting to dip again by Sunday. It is a welcome change from…