It really varies depending on your personal needs; I had an annual bus pass, so I didn't have to consider transport costs, but you might. Do you like going on nights out? You have to factor for that too. Groceries may usually cost about £40 (including buying toiletries and cleaning supplies); then you may want money to treat yourself too. Don't forget any other bills like your phone; and things like netflix or spotify if you use those. Always try and set some money aside for emergencies if you can too. Do you have to do your laundry at the laundromat at your accommodation, cuz that will usually cost around £5 a load too.