I wish to visit my son, UK citizen, marrying in China this autumn.

My son currently works in China on a work Z type. He has been living in Suzhou for three years. In November he will be marrying a Chinese citizen in Nanjing. I would like to attend the wedding celebrations. I would be in China for no more than a week. I am 62 years of age. I will not be staying in hotels for all of my stay. I intend to stay in Shanghai, Suzhou and Nanjing over the week.
What is the most appropriate way for me to get a visa....would I need an invitation from my son as verification of my situation?