Although you will be in class with fellow Americans, most classes are held in the University of London Union. This building is used extensively by students of all nationalities attending the University of London. Joining one of these is a great way to meet British students with similar interests, but if you make the effort you can also meet people in the coffee bars between class. Choosing a homestay is perhaps the best way to meet local people. Living in a London home will give you a real insight into how people live in Britain and most students get to know their hosts very well.
Volunteer work is also a good way to meet people.
The AIFS staff can arrange this for you once you are in London. The staff there will be able to answer questions on deadline dates, flights, billing or whatever questions you have. For questions about London, e-mail the student services staff.