Premiership Rugby are giving fans the chance to get 20 per cent off thousands of tickets to this season's Aviva Premiership Rugby Final in their Boxing Day sale.But hurry, this offer for a limited time only. Act now for your chance to be at Twickenham.   Fans from all 12 Aviva Premiership Rugby clubs will come together at Twickenham on May 28 for the biggest domestic match of the season and this is your chance to snap up a ticket for what will be an unforgettable day.   Visit the Premiership Rugby website to buy your tickets now by clicking here.