The RAF didn't originally buy the Harrier because it needed to operate off carriers, and it is not buying the F-35B for that sole reason either. There remain good grounds for a STOVL capability, look at present operations in Afghanistan and,at least till Jumper went, the consideration given by the USAF to changing a large piece of their 34A order to 35B to provide the same sort of austere capability. The only aircraft they have capbale of operating in such conditions being the A-10.
The F-35C will, by the time it enters service, only better than the Eurofighter in one capability, day 1 stealth. If the decision was made for the RN to go down the F-35C route, it would make even more sense for the RAF to continue down the Eurofighter route and cut another complete aircraft type out of their fleet with all the savings that would imply, leaving the RN to have to provide and support the entire training/logistics tail.
I think it best to leave sleeping dogs lie.