How can you map London’s population?

The approach of using maps and data together to look at patterns and understand the world is known as Geographical Information Systems (GIS). Here, researchers have taken census data for London and plotted it onto the Google Earth system:
http://www.londonprofiler.org/

What Maps and Data are available for Surrey?

This link will take you to Surrey County Council’s interactive map service, a good starting point for collecting and analyzing data about life in Surrey.
 http://surreymaps.surreycc.gov.uk/public/viewer.asp