You cannot buy a through ticket, but it will cost around £70 or $110 one-way in total. It’s a good idea to book the Hong Kong-Guangzhou & Guangzhou-Nanning trains in advance by email through an agency such as www.chinatripadvisor.com, www.chinatraintickets.net or www.china-train-ticket.com, or perhaps in person through a travel agency in Hong Kong. The other buses & trains can be paid for as you go along.
- Day 1, morning: Take a train from Hong Kong (Kowloon station) to Guangzhou (East station). There are a range of departures daily, including one leaving Kowloon at 11:17 and arriving Guangzhou Dong at 12:58. Fare about HK$190 (£17 or $28). A taxi from Guangzhou East to Guangzhou Main station costs about RMB 30.
- Day 1, evening: Take an overnight sleeper train from Guangzhou (main station) to Nanning, train number 2571 departing Guangzhou at 16:52 and arriving Nanning the next morning at 06:23. Soft and hard class sleepers are available. The fare is about 286 RMB (£29 or $43) in a soft sleeper, or 184 RMB (£19 or $29) in a hard sleeper. Spend the day in Nanning.
- Day 2, take the daily overnight train from Nanning to Hanoi, see the section above. It leaves Nanning in the early evening and arrives Hanoi next morning. Soft & hard sleepers available, fare RMB 229 (£23 or $37). Alternatively, there are several modern buses from Nanning to Hanoi every morning.
see: www.seat61.com for up to date reports on buying tickets and prices being charged to tourists, which often deviates depending on who sells you the ticket and the type of seat (or bed you wish to buy).