I have UK Passport and want to visit Ganzhou for visa on arrival

In case that you want to visit Guangzhou, you have to be aware that there is no visa on arrival. Visa on arrival is available for Shenzhen and Zhuhai cities only in Guangdong province. My suggestion is that you rely on 144 hour visa free transit for Guangdong province. This is the best option. To make your itinerary eligible, it should look something like this:

India - Guangzhou - Hong Kong
Hong Kong - India

You should fly directly from India to Guangzhou and from Guangzhou you can take a train, ferry or plane for Hong Kong. Having an itinerary of this kind will assure you 144 hour visa free transit in the entire Guangdong province.

Keep in mind that you will have to present your train, ferry or plane ticket from Guangzhou to Hong Kong at the check-in in India to be allowed to board the plane for Guangzhou visa free. Also, you will have to use exactly that ticket for your departure from Guangzhou to Hong Kong.

After you have reached Hong Kong, you can return to India or any other place of your choice.