I would imagine you could quantify it by looking at the economic gains of businesses having high speed internet access compared to the increase in taxation to fund it.
If this was my idea, I would cut spending in an area which isn't vital, such as parts of the welfare state to fund such a programme, so taxes wouldn't have to be increased, but I doubt that is what is going to happen?
At home, my parents pay for it and at university I pay for it with my student loan.
Noble thought, especially cutting spending in an area that "isn't vital," but who determines what's vital and what isn't? You? Any thought as to how much argument you'd get, whatever it is you decide you're going to cut?
Politicians very, very rarely cut a tax that they enact. They love spending that money too much to cut it. And continually seek to find other sources of revenue to fund their thirsty habits.
You're a young person. You have yet to find your own way. After some years of paying for not only your own lifestyle but other lifestyles that your taxes support, you will likely become sick and tired of paying for other people who are not only unproductive and lazy, but absolutely determined to remain that way.