I'm Italian and I live in England, I would like to visit my Chinese girlfriend, can I apply from Uk?

Yes, you can apply from UK. Your stay permit or residence permit will be required for submission.

I am not a student , I am a worker in the UK, so I can't submit for a stay or residence permit, reading a lot of info, I surely can say I am a bit confused now. then what procedures should I go for?

Dear, it’s okay. Your work permit can work, too. You can ask your girlfriend to issue an invitation letter to you. You should apply for a tourist L type to PRC.
You first need to provide your passport and its copy, the completed application form affixed with a passport-style photo, the invitation letter as well as your work permit in UK. Afterwards, submit your application to the CVASC to apply for it.