Robbie Williams thinks fame “should come with a health warning”. The 48-year-old singer is returning to Stoke-on-Trent for one-off homecoming concert at Vale Park and reflected on both the positive and negative sides of his career in the limelight – which started when he was a teenager in the boy band Take That. In an interview on BBC Radio 4’s Today programme, Robbie said: “I’m glad it happened to me when it did because there was nothing else happening to me.” The ‘Rock DJ’ hitmaker did liken “extreme fame” to an illness and feels younger people are particularly vulnerable to the perils of st…