If both ever have to deploy with a full compliment of 36 F-35s a piece
I believe the latest statements from the MoD indicate that the normal complement will now be 24 aircraft rather than 36.
The general consensus would seem to be that the F-35B is the most successful of the three models, both the USMC and RN getting the other services to pay enormous amounts of cash for sub-optimal aircraft so they could get a far more effective platform to replace the Harrier. The USN in the meantime seems to buying new F/A-18s and how many F-35Cs will be bought remains to be seen; whilst the USAF F-35A buy seems to be increasingly caught up in arguments and proposals for either upgrading F-16s, building an F-22/35 hybrid or bringing forward the proposed long range penetrating fighter.
Regards splitting the UK order for F-35Bs would more probably lead to an additional purchase of further upgraded Typhoons rather than any F-35As without probes.