As part of its service Professional Relocation provides its clients with a comprehensive overview of the chosen area. By way of example, here's the basic briefing on London for expatriate Americans:

LONDON, ENGLAND
This ancient city is still today the European – if not the world’s – financial centre. As English is spoken many American companies use London as their route into trading with the rest of Europe. As a result there is a large expatriate community in and around the London area – American, European and most every other nationality, too!

Housing
Housing is expensive. One, two, or three bed apartments (flats) may be purpose built or converted from larger single-family homes. They tend to be furnished. Larger homes and houses are mostly unfurnished although they do include major appliances and rooms tend to be small.