British passport holder want to go to Guangzhou from Hong Kong

I am going to Guangzhou on the 13/10/2014. I hold a British passport. I thought that I could get a visa from Hong Kong in order to enter Guangzhou. I've just looked at the Chinese embassy. Their service only provides a 3working day service as part of their "express" service. Does anyone know if there is an earlier service???

Pls help ):