I think you need to be clearer in your mind what you will need to spend.
So not just your monthly standing orders or direct debits, but all the irregular things you pay too
Things like your TV licence once a year, but I think you'd need to budget in about £13 pm to pay that once a year.
Then things like getting your hair cut. No, you don't need to spend vast amounts on it, but at some point most people do get a hair cut.
Someone mentioned presents. True, if you are down to your last pennies, they aren't 'essential' , but, most people get someone something for Christmas / birthday.
You mention in a post "all except electricity which is on PAYG". Well that is the most expensive way to have to pay for your electricity, so you need to budget a regular amount for that. Difficult for anyone on this thread to guess how much you will use.
Then you make decisions like not taking out insurance for things to save money, but then you will need to have savings to cover replacements of those items you consider essential if lost / stolen / broken - be that your fridge or your mobile phone.
If you are saving for a 'goal' for a set term, then it is okay to go to the bare bones of your spending, but if you are talking about long term lifestyle, then you need to allow yourself 'treats' - be that a short holiday or something much smaller like a night out or even a takeaway coffee.