Are there buses from Gongbei or Zhuhai that goes to Nansha town?

There is no direct bus between the two. You may take a bus to Panyu from Qiguan Port Bus Station near Gongbei Port (about 1.5 hours). The buses are available from 7:35 to 20:10, and the fare is CNY 65. Upon arrival, take bus line Pan 160 or Pan 162 to Haibang Station. Then, take metro line 4 to Jiaomen Station. Afterwards, take a shuttle bus to Nansha Port.