Almost impossible to say as we don't know all your outgoings or how you live.
You have rent (you may also have to pay a deposit on your flat), but also may have to pay for electricity and gas, water rates and maybe council tax. Also house/flat and contents insurance.
You also have to pay for phone / mobile phone / broadband, plus TV license etc.
You have your food and drink, any travel costs (bus / train to college or university), plus costs for books etc at university.
Plus any entertainment (cinema, computer games etc), eating out, drinks in pubs etc.
There are so many things you have to pay for it is impossible to give an accurate figure of how much it will cost you to live.