As an undergrad, it will be very tough to inundate yourself in WW2 studies. Obviously, you could pursue a degree in history and write your senior paper on WW2, which would allow you to spend a great deal of your senior year studying the war. I have to warn you, however--and this of course depends on the sentiments of the staff and your adviser at whatever school you attend--, you may be expected to analyze the war from a non-militaristic point of view, as military studies of the war have been done in droves and are falling out of vogue in any case. Changes in national identity (perhaps in an occupied nation), in gender identity, in class ideology--this is the kind of stuff many scholars study today regarding WW2. If you just want to study the military aspects, you'll need to do your research before applying to any given school.