Hmm... Then again, Ive just remembered a lightly loaded existing circuit passes through the loft over the kitchen.....

Perhaps Ill spur the bumble off that, and add a separate Socket for the F/F on RCBO using the spare 2.5T&E at a future date.

(Yes, I know it would probably never trip the ring MCB if it stayed where it was (unless we plug the cement mixer in at the same time), but Id rather not have the circuit stretched.
(Especially as Im unsure of its precise topology, etc).