London is famous for being one the most diverse cities in the world, and in certain suburbs of the city, you'll even find that English has almost become something of a second language.
Look for work within your community
My first suggestion would be to look for jobs in areas and communities that speak your language.
For instance, if Gujarati is your native language, you could head towards areas like Croydon or Wembley where there is a significant Gujarati-speaking community.
If French is your strong point, look for jobs dealing solely with French clients. Whilst your choice of jobs will certainly be restricted by your lack of English skills, finding employment is certainly not impossible.
Luckily, as I mentioned above, London is home to all sorts of different ethnicities and nationalities, so whether you are from Peru or Pakistan, you'll be likely to find an active community that can help you out.
Look for jobs that don't require much communication
Another alternative would be to look for work that doesn't require much communication or interaction with the public.
Unfortunately, these jobs often don't pay very well because the skill-set required is in such abundance, but looking for work as a 'kitchen porter' or a 'bus boy' in a restaurant is often the first job for many people who have come to London to experience the lifestyle and improve their English, including a number of foreign students.
Why not contact someone at your local Job Centre and see if they are able to give you further advice about employment in London? Alternatively, websites like Gumtree are also a great source of employment.