Application for Stay Permit at Guangzhou Airport

I am a UK passport holder and have a 12 hour layover in Guangzhou and would like to leave the airport to do some sightseeing. Will I need to apply for a transit visa at the Chinese Embassy in the UK before I leave or can I get a 24 hour Application for Stay Permit at the airport? If I can get a permit on arrival, is this a fairly easy procedure? Any advice would be gratefully received. :-)