10 years is a long time mate,
they would have to be pretty stupid to go for a full-size carrier, and here's why:
the F-35 is a support aircraft, a "diet-F22" if you will, it's there to help the F-22, work together with it, its carrier version is fantastic, but you don't build up naval airpower out of one aircraft variant.
Judging by the developement on the Israeli and American front, in ten years tactical UAV's are gonna slowly step in for human pilots and do the "dirty work". in which case a plane like the X-45 doesn't really need a big carrier, just one of those heli carriers the British navy owns at the moment.
the F-35 is set to replace the Harriers in naval action, it has V/STOL capabilities, like the harrier, and does not require a catapult, or a big deck.
now why would the British navy spend billions on a new carrier when its heli-carriers are perfectly capable of taking on these (or other similar) aircraft?
kinda reminds me of their decision to take the gun off the Eurofighter, that's what the US did with the original Phantoms, turns out that once you're out of missiles you can't shoot anything down with a "clean" nose

Iafpilot