I am a British citizen filling out a visa application form for China, but I am struggling on what to put as my flight number for my arrival flight as it is from the Philippines and contains two flights. The first is from Manila to Guangzhou, and then a second flight from Guangzhou to Wuxu Airport in Nanning. I'm concerned that if I put the second flight number that it won't look like it's my arrival flight on the application form, but if I put the first flight number, will I have to validate my visa on entry at Guangzhou?
Put the first flight which takes you into China. You will have to pass through immigrations in order to get to the domestic gate for your second flight.
You may also have to re-check your checked-in luggage as well.
So you list the flight that brings you into China from abroad, you do not list the domestic flight as you do not need a visa for domestic flights these days