The reason petrol is going up has nothing to do with the Government, it's down to the price of crude on the international markets so while tax on fuel in the UK might be high you can't blame the Government for some dealer getting up with the hump and deciding to move the market as his bonus will be higher if the oil price is higher.
As for reducing the tax, what the fuck do you expect him to do? We have to pay for the biggest spendup by any Government in history so that we're not left in the same position as Greece and Ireland, or would you rather put up with this crap for the next 25 years? Petrol isn't that much cheaper in Europe than it is here but check out the levels of taxation on other stuff in those countries, especially income tax and you'll see that we're not actually that hard done by.
There are plenty of other areas money could be saved, stopping the bullshit in Libya for one, maybe then the Government could consider a reduction in fuel duty.
Jerry