More Ticket change questions?

The best laid plans of mice and men and all that!!!
I'm on the final count down to my next holiday trip to PVG, but now it looks like a week earlier I need to be in Korea on Business.
I'm hoping I can persuade the company to book me something like London-Tokyo-Seoul then Seoul-Nanjing then Shanghai-London
Thus doing the meetings, getting to my holiday and mostly in UCS comfort at the company's expense.
And I hope the cost of this is around the same as London Seoul direct. So the company don't complain too much.
If not does anyone have any suggestion how I can play the n class ticket. If it works out right with the company I don't mind writing off the cost of this ticket, but of course it would be nice if I could change it to something I can use another time. What are the possibilities for paying to upgrade N to something flexible and do I need to specify future travel dates?
I'm trying to get my head around all the cost scenarios [:$]
If course I know what you mileage whores will say.... Fly LHR-NRT-ICH-NRT-LHR in UCS and get all those miles and points, and then get straight back on LHR-PVG-LHR and get all those miles and points too!
I'm on the final count down to my next holiday trip to PVG, but now it looks like a week earlier I need to be in Korea on Business.
I'm hoping I can persuade the company to book me something like London-Tokyo-Seoul then Seoul-Nanjing then Shanghai-London
Thus doing the meetings, getting to my holiday and mostly in UCS comfort at the company's expense.
And I hope the cost of this is around the same as London Seoul direct. So the company don't complain too much.
If not does anyone have any suggestion how I can play the n class ticket. If it works out right with the company I don't mind writing off the cost of this ticket, but of course it would be nice if I could change it to something I can use another time. What are the possibilities for paying to upgrade N to something flexible and do I need to specify future travel dates?
I'm trying to get my head around all the cost scenarios [:$]
If course I know what you mileage whores will say.... Fly LHR-NRT-ICH-NRT-LHR in UCS and get all those miles and points, and then get straight back on LHR-PVG-LHR and get all those miles and points too!