The CVFs were always designed with conventional aircraft in mind, that's why they're as big as they are. The ship size is determined by the length of flight deck, which in turn is determined by simple schoolboy mathematics given a known takeoff speed and the maximum force you can apply to the airframe without it breaking. The carriers are currently fitted "for but not with" catapults and arrester gear. It would seem rather retrograde in an All-Electric Ship to fit boilers to generate steam for conventional catapults, but will MOD take the risk to go for electric catapults? There's already a UK electric catapult under development, by the way, so we don't need to buy American: http://www.janes.com/news/defence/jni/jni100726_1_n.shtml
Andy