Dame Helen Mirren has urged the people of Cardiff to help raise money for homeless and vulnerable people in an appeal launched by Just Eat and Social Bite.  Other well-known faces including Rob Brydon and Sir Chris Hoy have posted videos backing the new Christmas Meal Appeal launched by Just Eat in partnership with charities Social Bite & FoodCycle. The appeal comes after reports detail the increasing issue of homelessness in the UK, and the increased pressure and reliance on charities as the…