Electricity is likely to be one of your biggest costs. Allow �70 per month:
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If the flat has a water meter, you'll not have very big bills. �20 to �25 per month might cover it. (That includes the sewerage charge which makes up much of the bill for light users of water). However, you'll pay more if your water usage isn't metered. (Possibly �40 per month)
Your telephone landline bill might be around �20 to �25 per month if you don't use it much. (Most of that is line rental). Remember to add on your internet subscription.
Contents insurance will probably cost no more than �10 per month.
Council tax will probably be around �55 to �60 per month for a single occupier.
Food costs can vary greatly according to your lifestyle. If you never eat out and don't buy takeaways, it's possible to survive on about �20 per month. (I know because I've done it but I definitely don't recommend it!). �40 per month will still see you living
very frugally. Most people would probably want to set aside at least �100 per month for food. If you eat a lot of chilled ready meals, that might go up to nearer �200. A couple of takeaways each week can add another �50, or more, to your monthly food bill. That doesn't include any booze. Just one night per week in a night club could easily add �100 per month to your bills. If you eat out and drink out a lot, add yet more money to your total.
Chris