as a *very* experienced renter of accommodation, the norm (for what it's worth) is this:
the usual facilities are split equally: so gas, water, electricity, phone landline standing charge and tv license are all split equally between members of the house, regardless of living arrangements. you may never use hot water to bathe, but you might wash your clothes everyday. you might never cook, but you might be using an electric blanket all night...it's swings and roundabouts, so split it all evenly. it also helps to focus everyone on energy saving.
the phone standing charge/line rental can be contentious, but if a member of the house has so much as given out the number once to friends or family, then they are taking advantage of it for incoming calls, even if they never make an outgoing call, therefore they pay their part of the standing charge.
'specials' are sorted out between parties. e.g. if you use the broadband, you take your share of the bill. if you don't have a computer or a wi-fi enabled anything then you don't pay. if you never watch sky in the living room because you're happy with freeview in your bedroom, then you don't contribute to the sky package.
mostly it's quite simple, and mostly it should all be clear and sorted before you move in.
oh, and usually the rooms do come in different prices - the smallest one should be cheaper than the others, especially as it's effectively a single room in your case and you can't even get a double bed in it.
This post has been edited by kissmequick: Jul 27 2011, 16:09