I discovered Ecover limescale remover from a friend who raves about it. (yes, I’m well aware of how tragic that sentence is! lol).
It’s great stuff, safe for the environment (and therefore little ones) and it does a FANTASTIC job of removing limescale.
It’s quite expensive at £4 a bottle and I’ve only ever found it in Ocado, but it’s the only thing that gets my shower screen clean that doesn’t have harmful chemicals in. It does an awesome job on metal sinks too.
Highly recommended if you want to get something that cleans but doesn’t have harmful chemicals in.