Well I wouldn't really discribe it as hidden cost, as they're quiet blatent about telling you how much you will have to pay. They'll send you a little booklet and give you the option of paying in whichever way you want to.
It's supposedly set to what kind of house, where you live, and how many people are living in the house (and whether they're on sickness benefit, unemployed or at school or not.). There's supposed to be a sliding scale to how affluent an area that you live in is, which is also shown in the figure of what you pay to the council.
It's uses are for paying the police, firemen, ambulance workers/paramedics, garbage collection, to repair pavements/sidewalks, paying for the maintainance of parks and many other publis facilities.
Other charges that you'll come across:
Television license,
Duty on cigarettes and alcohol,
When you rent you'll find that all of your household charges are all seperate. So, if you pay for rent that's all you're paying for.
