That bloke should do 1 of 2 or 3 things imho.

Save and get to Taiwan/Vietnam, which both have a lower cost of living, Viet perhaps more so than Taiwan, and never go back to China, even if it means divorcing his younger wife. Younger women are a luxury he shall have to forego.

OR:

Apply to Saudi Arabia/gulf jobs, return to the UK, complete all his attestation, and go to saudi arabia/gulf with his chinese wife on a marriage/supporting visa and teach there. He may however have a problem there, as a lot of the jobs prefer single males there, and he may need to satisfy the authorities that he can support his wife (hard to do if poor like you said!) and that she won't be trying to find work, or working illegally there, not easy. Hard enough for a single person to complete the process. The pay however would let him save, and the living cost is next to nothing.

OR:

Go back home, declare himself homeless, and struggle back getting into the system. Even though single and white and old he will be down the list, it is still an option. Pretty sure the dole is about what he gets there, which he has to teach chinese students for.

Either way, Nanning is no long term option for him.

Good luck sb