I have 2 year multiple entry Visa. My passport is stamped but runs out days after I return to uk.

I have already been to China in June 2016 for 3 weeks holiday.
I am going to China again in January 2018 for 11 weeks holiday and returning to UK early April 2018.
My UK passport runs out 18th April 2018.
My Chinese multiple entry visa runs out 18th April 2018.
Will any problems arise with the time left on passport for visiting.
I have heard that you need 6 months left on passport before going to China and is it ok to come back within days of it running out.
If a problem what am I to do.