It is possible to live and work in China without speaking Mandarin, but only if your job doesn’t require any language skills and if most of your local colleagues speak English. You will also need to have a local friend who is always there to help you with your social activities, administration procedures, and other stuff.
However, foreigners who are able to speak Chinese are having a much more comfortable lifestyle. Learning Chinese gives you the ability to talk to locals, go anywhere on your own to eat (even to small restaurants with no English menu), understand signs on the streets, and do whatever you want without the help of anyone. So, even if you don’t need to know Mandarin for job purposes, it still makes sense to learn it in order to have a normal social life and to experience various great things during your stay there.
If you want to take the Chinese language course, LTL Mandarin School is a good place to go. I would also advise you to take advantage of the range of Chinese learning resources available online. What’s particularly great about online tools is that you can learn on the go or whenever you have a break, which saves you tons of time. To have a better idea of where to start, check this guide: https://www.hackchinese.com/blog/a-pre-beginners-guide-to-learning-chinese. It gives some good tips on learning Mandarin for beginners.
I hope it helps!