British nationals ?

But, you are mentioned above although not as Great Britain, but as United Kingdom :)

UK citizens are definitely eligible for all visa free transit options, so if you travel from Vietnam to London and you have just one layover in China, for example in Guangzhou, you will be eligible for 144 hour visa free transit within the entire Guangdong province. The same thing is valid for Chengdu, Shanghai, Beijing...

Anyway, if your itinerary has two stops within mainland China, then you are allowed to use only 24 hour visa free transit. In other words, if your itinerary is:

HCMC - Guangzhou - Shanghai - London

You are allowed to have a transit of 24 hours length, staring from your first scheduled arrival, in this case in Guangzhou and until your last scheduled departure, in this case from Shanghai.

To summarize, one stop - 144 hour TWOV if the city is eligible, two or more stops - 24 hour TWOV.

That is exactly the itinerary I am thinking of !
Thank you Zufan for your swift and helpful reply.

If we cannot exit the airport . Hi can we use any hotels to stay on transit ? If yes which hotel is it ..thank you

Be aware that the 144-hour transit is not available to holders of British passports who are not British citizens.