English corner is a very popular concept among people learning Enlish in China, and actually that's how I get the idea of doing a Chinese corner here. Back in China, since English is the most important second language and a compulsory subject in high school and college, native english speakers are warmly welcomed especially at English corner, basically what we do there is that everyone would try to speak English there in small groups, and the topic could be anything interesting, and a native English speaker would often become a center of each subgroup, and it is generally regarded as an effective and efficient way to learn a different language and the culture behind it.
As I understand that Chinese is a much less popular second language than many other languages here in UK, so I think we could first start the Chinese corner by introducing Chinese language and culture in English, and also do some simple everyday oral Chinese practising there.