Remove existing shower isolator, replace with an RCD FCU, connect new bathroom lighting to that.
Optionally change MCB in the consumer unit to some lower value. The 45A shower should never have been fitted in that consumer unit, as it is a maximum of 30A per way.
Optionally change MCB in the consumer unit to some lower value. The 45A shower should never have been fitted in that consumer unit, as it is a maximum of 30A per way.