Urgent advice please on Transit visa policy in China in 2018

We are flying to Tokyo via changing planes in Beijing and then after 2 days going on a cruise to Shanghai, then we are staying in a hotel in Shanghai for 3 days, then flying back to London (we both have British passports) via Beijing where we have 2 hours to change planes. This is an organised fly/cruse package with Cruise Nation but they cannot help us with visa info. Will we be ok with the 72 or 144 hour transit free policy entering Shanghai by cruise then leaving 3 days later? We will have of course onward flight tickets. Please help urgently as we are sick with worry have read all sorts of advice and its only answering machines at embassies in UK. Thanks