Are German and Chinese useful languages to become a translator?

I'm going to be starting a degree in them in September..
Will I struggle to find a job in this sector?

Not at all, far fewer people study German and Chinese than study, for example, French and Spanish. I did my degree in French/Spanish/German and when I became a translator German was by far the one I got the most work in just because there's a shortage of people. If you have Chinese too then you should be well set!

To make a proper go of translation you really need:
- Specialist translation qualification - either Translation at undergrad or languages at undergrad and Postgrad translation
- Membership of a professional association such as the Institute of Linguists
- Experience - this doesn't need to be paid. Look for volunteer translation opportunities on the internet, or you could advertise to researchers/PhD students etc at your university that you will translate foreign journal articles etc for them for free or for a nominal fee so they can use them in their research.
- A specialism can also be a massive boost. Specialisms in demand include law, medicine, science, engineering, etc - so if you have any interest in something technical, or say, an A Level, then try to get experience in this area as you're more successful as a translator with a specialism.

Good luck!