What visa and where do I apply?

Hi there, I am a New Zealander, with a NZ passport, originally born in Hong Kong. I am going back at the end of the year, but the family wants to go to mainland China to see my Grandfather's place for a few days. Which visa will do I need, and also I am currently living in Spain till September, but then will be in the UK. I am currently on my OE on a Youth & Mobility UK visa. Where are the offices in the UK that I can apply? And do I HAVE to go in person? And where is the price list? Cheers