Petrol and diesel prices on the forecourts are volatile. No matter what happens to taxes, if we have already passed peak oil, or soon will,  the price of oil can only go in one direction: up. What can you do about it? You can downsize your car (gas guzzling 4x4s are so last year). You can drive more carefully. You can drive less. You can hunt around for cheaper petrol. Or you could say, 

"Because I do not own a car, I really am not bovvered."

Let other people do the worrying about petrol prices: Give Up Your Car, and get on with your life.