Hi, I have a british passport and am living in Riyadh. I hope to go to china on the 22nd April

If you go there for tourism purpose, you can apply for a tourist L type there. First, prepare the required documents including your passport and copy of its data page, the completed application form and a recent color photo, your valid entry permit to Saudi Arabia, as well as round trip air tickets and hotel reservation. And then submit your application to any of the following three offices to apply for it.
Foreign Affairs and Business Office
Chinese Competitive Spirit Co. for Visa Service
AlSandross International Est.