The whole UK Carrier/Carrier Fighter project is in a right old pickle. It will now take a lot of luck for it to come together in a positive outcome for the UK.
The US has backed off from large scale commitment to the F35 (all versions) ostensibly for cost reasons but also because they have fallen out of love with the concurrency fantasy too. Not until the 2020's will they order in significant numbers (significant for them that is). If the fighter does not come up to scratch, they could still bug out even then. The US naval forces have hedged this risk by ordering more Hornets and the UK's Harriers to help keep their AV8's going for longer, and the USAF by committing to F16 upgrades while considering both capability and airframe life extension upgrades to it's F15 fleet.
So while the US doesn't actually fully commit to the F35 for another 8 years, we and other nations find ourselves in a situation where we may have to before the launch customers. This is not a good place to be, and other buyers like the Australians and the Canadians are beginning to get understandably nervous about the timing conundrum they are faced with.
The UK's response is political, sorry I mean strategic: it has deferred the decision until 2015 when the next strategic defences review is due. As luck would have it that's when the next general election must be held too, so there is every prospect that any unpopular decisions can be left to the next administration. But even leaving it until 2015 requires the UK to show more faith in the aircraft that it's launch customer - not in absolute numbers maybe but it will be 100% of our fixed wing naval capability. The US will still have F18's and AV8's to rub by with. Maybe not what they want for the 2020's and beyond but they will still have something proven. We will have only helicopters to turn to while we await UCAV's or something else.
I don't see any perfect ways out of this mess for the UK. In my opinion the best solution would be to buy or lease Super Hornets. If the UK carrier(s) survive the 2015 SDR (not a foregone conclusion by a long chalk), then we can work up a very credible naval air strike component that could survive until 2025 at least, while re-acquiring carrier operation skills in readiness for F35 beyond 2025, if it has proven itself by then. F35 cost will be known, it's capabilities will be better known. If stealth has been busted by then, you might not want to pay so much for it. Whatever, you make your choice with a whole heap of currently critical 'unknowns' now very much 'knowns'.
And if the 2015 SDR cans the carriers, well we could still order F35A or B (proven as above) to supplement Typhoon, or the long range bomber, or UCAV's, or more Typhoons, or continued investments in nuclear attack subs, or a combination of these. At least we would be in control of our options, as opposed to only be able to react to unfavourable circumstances that could be forced on us by others.