you don't need to go round E&c there's a brilliant cycle bypass. I go from ED to Oxford Circus via Peckham, Elephant, Waterloo and Soho and here is my route if that link doesn't work you can also see it here Its great and there's nothing too scary. I don't do the canal path I take it quite easy, stop for red lights and don't filter unless its very safe to do so and it takes me about 45 minutes to do the 7.75 miles. This is another version that goes via Dulwich Village and avoids big roads, you cut across them and there are good lights, a wiggle round Kennington Park, over Lambeth Bridge, by Green Park up the Mall cycle path then wiggle through Mayfair to Oxford Street.