Dame Helen Mirren doesn’t feel worthy of a lifetime achievement award. The 76-year-old Hollywood legend is set to be honoured with just that at the SAG Awards in Los Angeles next week, but she has admitted she doesn’t believe she is deserving of such an accolade, despite a storied career. Mirren already has an Academy Award and a British Academy Film Award for her portrayal of Queen Elizabeth II in ‘The Queen’, a Tony Award and a Laurence Olivier Award for the same role in ‘The Audience’, three BAFTAs for her performance as DCI Jane Tennison in ‘Prime Suspect’, and four Primetime Emmys. Of her…