Zhuhai visa

Currently Australian citizens need a 3 days Zhuhai visa on arrival. Since you have mentioned that Zhuhai is the place you will visit, this is by far the most practical. You do not need to obtain a visa in advance, but you will apply for one at the border crossing. You will decide which one border crossing you will take, but arrive there within roughly 09:00 - 16:00. By the way, there is an announcement that Australia citizens will receive a visa waiver for up to 15 days visit to entire mainland China very soon, but so far the exact date is still unknown.