"Lead the charge" is a military concept: one person leads the rest of the soldiers into the particular battle. My assumption here is that of all the foreign students at British schools, the Czechs are the greatest in number. The "headline" seems unusual to me.
Hello everybody, thank you very much for all your replies, you have helped me a lot! As I am going to analyze an article with this headline (from The Times) for one of my linguistic courses at university, I really wanted to be sure. Thank you!