I reckon you can probably find a decent room to rent in London for £650 incl. bills. Add on the local council tax (£65 to £120) and commuting. If that’s affordable, go for it.
London is ace if you have a bit of spending money. It’s crap if you’re skint and have no friends or family to help out.
I’m in London, from Sheffield via a couple of places on the continent. I’m not going to stay here forever, but I’m glad to have spent a few years here. Ignore the brexiteer Yorkshiremen, they’re wrong about this place. Mail in profile if you want some advice.