I don't think it is a lot, in London. Esp if you have kids and are the only earner.
I earn a bit less that that but not too much. After tax and pension payments, student loan repayments and my half the rent on a (albeit reasonably nice and central) 1 bed flat I'm not rolling in it.
I do go out for meals and drinks with friends probably 2 times a week and don't had to worry about things like that but I hardly spend any cash on clothes and we eat cheap veggie at home (DP Is veggie, and I love cooking). I prioritise cash for holidays and go away probably 3 weeks a year, usually 2x ski trips plus something else. My other weeks holidays have been spent at hole or at my parents going out for local hikes. I don't have any CC debt repayments to worry about. Oh, to keep my car running that was £800 insurance plus tax, MOT, servicing and parking permit. So basically 2x months 'disposable' income (cash after rent).
So although I have a nice lifestyle, if i had kids I wouldn't be able to afford ANY of the nice trappings of my life. And if I had to pay the full rent and bills on the flat I would only have £400 a month left over which would be a struggle and would leave no room to save for a deposit or ski trips.
So yeah obviously I could move to a flat in zone 6 or something and stop going out with friends, but I guess like other people are saying you his grow to fit your income.
My job involved a training period on a much lower period. Common talk of "when we're qualified we'll have so much cash" People who had already qualified always said you'll feel rich for about 6 months, then you'll grow to fit yor income. And they were right!