Hey, I'm in my first year studying Business and Japanese at Manchester
I've lived in China and I study Mandarin here as well, outside my degree.
I'm not sure about single honours European languages but the students who do single honours Japanese definitely have less credits than joint honours students. I believe they have 100 compulsory credits while we have 120 (which is also the maximum). It's a lot of work anyway, but yeah, they do have less hours and exams.
Manchester does have a BA Chinese and Japanese as well, I know a few people doing it and they're very happy about it.
If you have any question about it, I'd do my best to answer them. Good luck with your application