Teacher Discussion Forums

I am new in the TEFL business and need some advice from teachers who have experience with summer school jobs! I have been offered jobs at a couple of schools in London (7-8 week contracts, £205/210 pw) but am not sure which one to choose... Has anyone ever worked for EmbassyCES or ISIS in London?

Doea anyone have any knowledge about which summer schools in London are good employers? I have heard that ISIS is good. Any comments??