transit visa requirements from UK to Shanghai

I need to travel to Shanghai from the uk for business next week ( actually this coming Sunday). I am too late to apply for a visa ( embassy national holiday). I want to know can I use the "transit visa for 72 hours" idea.
I know I cannot fly out of London and back into London three days later but how about if I flew out of London but returned to say, Frankfurt or Amsterdam Then I can book separately to return to uk.
I am afraid they might say NO at Shanghai airport if my onward flight is not a plausible destination (like NZ or Australia for example). Does anyone have any experience of this?