If you want to lobby, do it quietly...
I have also heard that the amount of fuel used by GA in one year amounts to 15 minutes of London rush-hour traffic. I've also heard that it equates to less than the amount of fuel that evaporates from car fuel tanks in a year.
However, I would be very concerned about lobbying the Guvmint to lower Avgas duty rates in the form of some public debate or petition on the PM's website, given Avgas is currently taxed at half the rate of road fuel. Can you imagine the response from Joe Public if they heard that 'millionaire' pilots were paying half the duty rate that are paying for their road fuel?