I worked in Croydon for a bit... my route was Lordship Ln, Sydenham Hill, Crystal Palace Park Rd, Anerley Park, Anerley Rd, Auckland Rd, Whitehorse Lane, Whitehorse Rd. Could be in central Croydon in 20 mins. Maybe leave 30-35 mins on a Friday evening? Avoid the Crystal Palace triangle and the Sydenham roundabout.