There are certainly places in England where one can -- or, at least could prior to this budget -- live alright on much less than £17k.  I did when I was in Notts.  I think I was going on a bit more than half that amount, and I was in decent shape.  (I'd have no retirement savings if I lived on it throughout my worklife, but it was enough to pay the bills and live in a decent area.)  But Nottingham is, obviously, not London, in terms of prices.

How does Budapest stack up against London, as far as cost of living is concerned?

Be nice to America. Or we'll bring democracy to your country.