Where in London did they film the neighborhood scenes?

No idea but it doesn't look like London at all. Maybe France?

I don't know if this helps but the train station Richard is at just prior to finding out the company is foreclosed was labeled Watling.

Not sure about the houses, but the high street shots at the beginning were filmed in Dulwich Village in south London

the houses do not look English at all. I suspect they probabaly filmed those scene in France

In the interviews features among the extas on the DVD, it is mentioned that the entire film, including the scenes set in England, was shot in France.