What steps do i need to take to take in order to obtain an entry permit?

Yes, you need to apply one in advance. In your case, you just need to apply for a L type. If you ask your GF to send you an invitation letter and copies of her passport infomation page and resident permit, you won't be required to provide hotel booking and air tickets. After you prepare all required documents, you may visit some travel agencies and ask if they can apply for you.

There are soldiers who apply Chinese entry permits successfully. However, since their identities are sensitive, there are some people who were refused at last. Good luck to you!