I need to travel to China I hold a UK passport how do I get a visa

Margaret, you can apply for a tourist L type to enter PRC and buy goods. The first step is to prepare the required materials including your passport and its photocopy, the application form, a passport-style photo, the downloaded and signed declaration round trip air tickets, and hotel reservation. And then submit your application to the CVASC to apply for it.
As for the shopping mall, you are advised to go to Guangzhou Baima Wholesale Market or Yiwu International Trade City. You can find what you want from there.