Where does the cruise leave from? If from inside the Schengen zone I'd say the whole 14/15 days would count.
If from the UK I'd say from day of arrival in first Schengen country to departure from last.
Which ship are you going to be on and where? Performance can vary considerably.
If watching live sports is very important to you, I wouldn't be relying on Cunard internet.
I'm sure your review would be of interest on the Cunard board.
We often get questions comparing the 2 lines so a recent comparison would be very welcome.