I cycled in London for several years, before I left.
Don't consider the route you drive, or that the bus takes. That's the awful main road.
Look on opencyclemap.com or similar, and see where there are quieter routes. Many areas of London block off residential roads with bollards, which let bikes through. Over half my commute to work was along the Thames Path, and most of the remainder along a road so narrow most cars avoided it, with these bollards in the middle.
Don't consider the route you drive, or that the bus takes. That's the awful main road.
Look on opencyclemap.com or similar, and see where there are quieter routes. Many areas of London block off residential roads with bollards, which let bikes through. Over half my commute to work was along the Thames Path, and most of the remainder along a road so narrow most cars avoided it, with these bollards in the middle.