You'd probably get a 25% single person discount on council tax.
Electricity and gas can also vary a lot - I use approx £40 per month for the two combined in a 2 bed Victorian end terrace with single skin walls and no other source of heating.
I run a mobile for £7.50 and my broadband for £16.50 (line rental only got the broadband free).
My home and contents insurance is only £90 per year but I assume that goes up a lot with London house prices.
Might be worth looking at what you get if you move out of London, though I can see it's unlikely to be practical. I run my house inc all bills (car tax, broadband, Spotify, Netflix, to licence, water, gas, electric, council tax, mortgage) for under £660 per month in a two bed. The nearest railway station is 1hr 5 into London so probably too far to commute, but you can get a lot for your money elsewhere.