By Tim Hanlon Brits set for an Arctic blast with temperatures dropping to -6C can see on a Met Office map if they are likely to be hit by heavy snow. After milder temperatures in midweek, the mercury will plummet by Friday with cold air sweeping in and when it meets rain clouds coming from the Atlantic it will lead to flurries of snow in some areas. Weather maps show cold Arctic air moving southwards over Iceland and passing through Northern Ireland before reaching the UK. It means that north west England and parts of Wales, as well as Northern Ireland and southern Scotland could receive up to…