Well I commuted to work on my bike in London for years. I worked in Walthamstow and a couple of miles of each ride involved either the North Circular or the hellish road up to Chingford past the old dog track from the Crooked Billet roundabout. I never had altercations with motorists. The keys to being safe in city traffic are to give yourself space (no riding in the gutter), don't allow motorists to overtake if there isn't room, take off from traffic lights as fast as you can (making sure that motorists also waiting for the lights can see you) and to move fast. Fast is safe on a bike. You need to practise looking behind without wobbling. You shouldn't break the law at traffic lights. If you face a long wait, or if the junction is staggered or complex, you can always dismount and walk your bike across at pedestrian signals. There's no shame in it. If you are being reasonable and staying within the law but drivers still get cross with you, that's their problem. They are bring a hundred times less environmentally friendly than you so you have the moral high ground. But always know when it's just best to get out of the way. And I never, ever wore Lycra. My Sam Brown belt was always with me.