At the Open Day the Chinese teacher, who gave the Chinese talk said, that it really depends on the individual student on how fluently one can speak after the degree. However she stated that normal students reach level 6 in the HSK test(which is something like the TOEFL for Chinese) after the year in Beijing. Good students even reach level 8 according to the teacher. In my opinion that is really great, you may not be fluent, but at most chinese unis you have to get level 5 or 6 to study there, so 6 must be pretty good I guess.
Surprisingly she also said that at the end of the degree in general the students who did joint honours are more proficient in Chinese than those who did single honours, although the latter can spend more time on improving their Chinese. She said, that it might have something to do with the fact that students who do joint honours tend to organize their time in a better way.
In fact I think that due to the intensiveness of the course you will come out with a pretty good level of Chinese after you graduate, although it might take some more time in China to become fluent