Do you know anyone that currently lives in a 2br terrace that could give you more accurate numbers for the utilities? There's no sense in allotting more to gas, electric, etc. than you really need - especially not when other areas of your budget need the money more.
My husband is the ultimate bargain shopper - his grocery expenses were probably around £100 a month, including lots of tinned soup and curry as well as plenty of milk and fresh veg. When I moved over, our grocery expenses went up to around £250-£300 a month - partly because I eat more meat than he does, but largely because where he fixed a half a can of soup for dinner before, we now cook together most nights. Last night we had stirfry that fed us both well and probably cost a fiver to make, but even eating like that for a month is £150 just for dinners!