If the CU is being moved 6ft up the wall, its not going to be at a regulation height, ie it'll be too near the ceiling. You'll need steps to reset a breaker.
Nothing wrong with using battery powered smokes with radiolink interconnect from Aico for example. More expensive to buy, but saving time on install. (4 detectors, 30 minutes tops) and theres no cables to run under floors etc. No damage to existing decoration.
The only thing not regulation with the board is that its plastic. Buy a metal one yourself and use the existing breakers. Just has to be the same make of board.
Is this electrician already doing work for you or is there a chance of getting other quotes?