What? UK MoD will buy J-35 before they spend billions and years on converting the carriers to CATOBAR. That's not happening.
I agree with the first part of your sentence.
But both carriers were built with provisions to operate with CATOBAR should the STOVL system proves to be inefficient. It is almost like FFBNW. The construction of the deck, under deck and overall systems are ready to accept the fitting of a catapult and arresting wires. But the cost involved will most likely deter Royal Navy from adapting it. It is not just the conversion of ships’ hardware; But the teams that are needed for the CATOBAR are very special. I remember reading a Royal Navy expert’s view on the subject that these teams are trained for 40 weeks with 50% failure rate before they are chosen as operative teams. And they are continually tested and continuously trained to be at their best as it is an unforgiving job. This is not cheap. Your naval force needs to have deep pockets like US Navy.
Also having only two ships is a big factor as these carriers are also used as LPD and LHDs, both carriers may not have the full complement of jet fighters on board. So keeping crews and equipment for both is a costly process.
According to Royal Navy, the F-35Bs may trade off some range and payload yet they are still an excellent performer for STOVL capability. That provides flexibility and a high sortie rate. Old Harrier pilots have all commented how much easier it is to control and fly the F35B.
Infact some of the non-STOVL specific innovations of the UK’s Naval Air Warfare Centre had come up with, went into the Ford-class carriers to do the same improvements for the USN. UK and MBDA are developing most of their aerial attack munitions with a view to be used by F35B.
Also to be remembered that with F35Bs, turn around times are quicker and sortie rate is higher with STOVL and
they can operate in rough seas (e.g. South Atlantic) when CATOBAR aircraft are grounded. Add to this the smaller number of planes deployed from each carrier, the F35B is the ideal choice. That is why Italy now is adopting them, with Spain to follow suit soon. Also Japan is to do the same as they are buying 42 of the B version.
South Korea has dropped their F35B project and have chosen to go along with UAV carrier. With our KE and Anka3 we should follow suit with the South Koreans.