How long should it take?
It should take a certified electrician a full working day to replace a fuse board and carry out electrical testing to the existing circuits. Work which may also require upgraded meter tails and a main earth cable. If the electric meter isn’t located adjacent to the existing fuse board, it could take a bit longer.
Will there be much damage?
If the fuse board is located adjacent to the electric meter, there isn’t any reason for a competent electrician to cause any damage to walls or ceilings. Consumer units are normally larger than old fuse boards, which will cover any existing fixing holes or any cable entry holes.