Yay, I agree about the SPL was quite confusing at the beginning. Both my husband and I initially didn't think of the needs about it until his mates encourage him and don't miss out the benefits he entitled to.
The concept of SPL apparently was also relatively new - like a couple of years ago (?). That's why not much people familiar with it yet.
In very simple terms, both parents could share the leave make up of 12 month leave. Say using my example the mother takes 6 months, father take 3 months. It could be at the same time or one after the other. This would depend on the company. Other details say the 3 months have to be in block or anytime within first year of the newborn.
But the other element about it is the pay (which in our case is really the driver of how we plan our SPL). Using the 6-3 months example, I could take 3 months off with approx 100% pay and 3 months off statutory pay. in my husband company case, he could take 3 months off full pay. Again the payment pattern is depend on the company policy. So in this case, if my husband didn't take the SPL, he missed the chance of full paid off for 3 months. (And some of his colleagues post online about how incredible the SPL is, posting photos they doing childcare in south of France 😳)
and in total, we decided to take 9 out of 12 months of SPL, six from me and 3 from my husband. if he or me want to take extra 3 months, we both won't get fully paid.
Hope it helps!