My first post in English

Hi! It's my first post in English.
I will go to London tomorrow and it's the first time to go to country that I am going to a country where English is spoken as the official language. I stay in France now, so I'm looking forward to going there but I'm also a little worried as to whether I can communicate well. This is because I have not had many times opportunities to listen to British English. I heard that it is different to American one English.... Anyway, I hope that I will have a good time in London.