Rinse with vinegar. Alternatively you can also fill the kettle with 4 fingers deep water, pour in vinegar and then boil. Be careful to keep the water much lower than normal, but with the binegar on boil it just nukes all the limescale. You can also leave it in a bit longer.
For the rims dip sponge (rough scrubbing top) into vinegar and brush the limescale off.