The classic way to think about London is either North vs South or East vs West.
There are plenty of places in the North or West that I would consider less desirable than places in the South and East.
In reality, London is a collection of neighbourhoods and villages stitched together by buses, trains, trams, and of course, the Underground.
So instead of trying to you give one overarching way of thinking about London, here are some general rules of thumb (all of which have exceptions, of course): trans It's next to impossible to cover all the areas in London in any meaningful way.
Though I've never had anyone complain to my face about me being an immigrant, I have been involved in a couple of conversations where people complain about immigrants/immigration/foreigners in general.
When I've pointed out to them that I'm also a foreigner, they generally say something along the lines of Still, in my experience, this is an extremely rare conversation to have and it's one that you could have anywhere.