you need to get your pass person to look up a total cost for you to nonrev to London. Currently, you can fly thru CVG for LGW only, as an option. The gateway city is not much of a cost issue--it's the total miles/taxes/fees. They can set you up as a pass rider, submit your preference of flights/airports and give you a price. They can delete you after checking. Of course, no guarantees for next yr tkt price.
You will likely have NW flights by then, so anotehr consideration.
I would always plan to arrive at least one day early if you have a drop dead date--even 2 is recommended--WITH Plan B if you don't make it! Like fly to DUB and take LCC or fly into CDG--take the chunnel....
That's a whole year away! Are you saying youre going to London first, then going on your study abroad elsewhere?? Not sure about your general plan.