Getting a visa for China

Hello, I am currently travelling around South Korea, I am also planning to travel to Japan and China. I am a British citizen and understand that I do not need a tourist type for Japan however I will need one for China. How can I go about getting this? As I just have a tourist type for korea I understand I will need to get my permit for china in Japan.

Can you give me some info on how to go about getting this.

Thanks