By Nicola Fahey Robbie Williams and Rita Ora are among the first artists to sign up for a star-studded benefit concert to rival Live Aid and raise millions to fight climate change. More than 30 of the biggest names in music are expected to perform at stadiums in London and LA next year, alongside Robbie, 49, and Hot Right Now singer Rita, 33. Other acts approached for the fundraiser, being billed as Climate Aid, include Justin Bieber, Katy Perry, U2, Imagine Dragons, The Eagles, Bruce Springsteen, Ed Sheeran, Sia, The Weeknd, Tiesto, Billie Eilish and Santana. It is being produced by ITV ’s c…