my attitude is, when im driving the car i wouldnt want a prat getting in my way so i try not to be a prat getting in the way when im on the bike. if im on the line at the lights, get away quick and dont give them any reason to think bad of you, and then next time they see a bike coming they might move over a bit
(it is actually against the highway code to cause another road user to change speed or direction by your actions, joining the motorway at 40mph is a prime example, just die already you hat and driving glove wearing blue rinsed old gits)