Chinese Transit Visa in Guangzhou for a period up to 24 hours

Hello there,
We are two Slovak citizens traveling as tourists from Vietnam to UK. We have a stay over not longer than 24 hours in Chinese city of Guangzhou. We would like to leave the airport area and visit the city within the 24 hours time period. We have onward tickets as well as a hotel reservation per one night in the airport area can be provided as a proof.
Are transit G (or any other type) necessary?