We didn't have young children in the family so I knew nothing at the start.
I got confidence interacting with a wide range of children from a wide range of ages. (we were eventually placed with a 2.5 & 7yo)
I learned what the 'average' child could / couldn't do at different ages.
I saw discipline techniques in use.
I saw quiet children, confident children, clever children, less clever children.
I learned how to help them without taking over.
I learned how to praise pictures even when I had no idea what they had drawn (oh, I love the colours you have used, tell me about your picture)
I saw a wide range of activities which I was then later able to reproduce with my own children when they arrived
I got to know parents in our town that I then sometimes 're-met' at childrens activities after placement
I volunteered for 2 years, from after our training course all the way through until just before intros. I used to really enjoy it.
You could get approved without childcare experience, perhaps (though I doubt it). But you wouldn't get matched, or it would be loads harder. Why would a child's SW place with clueless you rather than experienced other person.
If at all possible, I would talk to work about whether, if you could find somewhere, you could do flexible hours, or a shorter week or whatever.
But ask your SW what sort of experience they are looking for, it is them you have to please.