Lindsay Lohan has fuelled rumours her romance with Samantha Ronson is back on – by flashing a “wedding ring” during her visit to London. The singer/actress was on a low-key trip to the UK while Ronson was in London for a series of DJ gigs this weekend. And gossips were sent into a spin when Lohan hit the city’s clubs on Saturday evening – proudly showing off a gleaming band on the third finger of her left hand as she left the Bungalow 8 nightspot. An onlooker says, “Lindsay has gone to …