Assuming you have a full British passport then the following applies: You will get the visa for Vietnam and Cambodia on board ($25 and $28pp respectively);, you will be covered by the ships visa for Sanya, BUT as you are disebarking in Shanghai then you will need to get a visa for China before you leave. If your ship calls elsewhere to Shangai (excluding Sanya) then you will need to get a multiple entry visa. If you google 'chinese visa' you will see the link to the chinese embassy website and you can request the visa there. I am very surprised that your T/A has not furnished you with all this info as that is what you are paying them for and it is their responsibility to ensure you have everything you need prior to travel. I hope what I wrote makes sense.
That's great - thanks for your very comprehensive answer. Our TA was as much use as a chocolate teapot and told us that we would need to contact RCI nearer the time as he only received conflicting reports.
Thanks for taking the time to say 'thanks'.....and I wouldn't use that TA again!!! Make sure that you sign up for the meet&mingle party that they throw. You go to royalcaribbean.co.uk >contact us> FAQs > and then under the On Board section it tells you how. You will have to register (it is free). It is a private party, the Captain attended our last one, and it is an excellant way to meet and converse with your fellow travellers before hand, and you can chat with them about sharing shore ex etc.