Gladrag - have to disagree with that (though not the logic behind it). The original design concepts done in 1996-ish IIRC all looked like a CVS that had been fed steroids and the f/w assumption of choice back then was what was known as SSF (STOVL strikefighter) - essentially the MDD a/c. Imagine the surprise when that didn't make it to demonstrator stage!
As for having a tea-kettle, that idea was binned around the same time, without much detailed study as I recall, largely on the basis that the USN were having an absolute nightmare disposing of their CGN and SSN/SSBN. One of the driving factors was the perceived difficulty and expense in disposal - remember we now have upwards of 15 decommissioned boats sat in Rosyth or Guzz, some of which have been there since 1980 or so.
In terms of capability no-one would dispute that a CVN would be somwhat better than an F76-powered ship, but as GBZ points out, there would be major hits elsewhere. The thing that would really kill it would be the need for more than two ships (given reactor overhaul and refuelling timescales - yes it would need refuelling for a 50yr life) to guarantee availability which was one of the planks of the ST(S) dossier - two big ships for the price of three smaller ones based on much improved (?) / reduced maintenance demands.
More to the point, due to the endless dithering over letting the contract, we're now in a position where there is no plan B and no time / money to generate one. UK Maritime aviation has essentially bet the farm on CVF and to a lesser extent Dave B. The ship is at least big enough to adapt to most things and that's it's big plus point - I'm sure there will be a number of emb8ggerances due to the h'apporth of tar savings that will be applied, but they can be rectified over time.