But for some context, West Hampstead is a fairly nice suburb on three different train and tube lines.
The rent for a one-bed flat is high as they are bid up by couples who are both earning. You are at a big disadvantage looking on your own. In my experience there is not much difference between prices for a one or two bed flat.
I think a big problem is the price of national rail transport into London from the commuter belt. It can easily cost £4,000 a year for a season ticket, wiping out most of the saving on rent or mortgage payments compared to living in the city.