Yes, all schools in London use English and most of them are British.
If you are referring to the language then you should know that in the UK we NEVER call our language "British English", that is just something invented by Americans. We just call our language "English".
All schools in London are also in both Britain and England, as that is their location.
What are you actually asking? Do you want a language school? (there are many)
You want an ESL program? There are thousands. You'll have to do a Google search.
And what is your question?
