So the reason more people are cycling in the area is that the government made cars extremely expensive, almost certainly more than the externalities created by those cars. If they instead instituted a carbon tax and congestion pricing, I doubt your daily expenses would exceed £12.50/day.
London's had congestion pricing for 20 years. The ULEZ is a tax on high NO2 emissions, not carbon. It's caused a significant reduction on the externalities of bad air quality, which was the goal.
