Sorry, I wasn't aware that this is a property you rent out. In all honesty, we're two decades into the 22nd century, and it's time that all circuits in all domestic properties, rented or owner occupied, are RCD protected.
To avoid long distance hassle in the future, resulting from earth to neutral faults, I'd advise that you specify an all RCBO CU for the replacement, rather than an RCD split board.
100000% this
rcbo board everytime , if you get a fault it is isolated to just one circuit.
if you have a split rcd you lose half the board which is a giant PITA