I have two children (a bit younger than yours) and me and my partner work from home, without any issues (from 3pm we have them both at home as there's no after school club and we have no family).
It's maybe not perfect, but they play together just fine and barely need us. I still deliver on all my tasks, meet my deadlines with ease, and consistently get great feedback from colleagues. If there's an important meeting, I keep the door closed, and the kids know not to disturb me.
We have worked from home since the onset of the pandemic, and the kids were still very young then, and at home since nurseries were closed, so they have learned that we are not always available for them, and instead to play together with their toys, in the garden, or watch a movie. For what it's worth, they are happy, healthy, loved, do well in school, and best friends with very few fights.
During the bank holidays I plan fun activities, and the remainder of the holidays they are in holiday club 2 days (which only runs 10-1). For summer holidays I still need to find a holiday club, and I will take 2 weeks off and so will my partner - so 1 week together as a family, 2 weeks with just one parent, and holiday clubs for the other 3 weeks. There will be occasional days where they are 'on their own', and perfectly happy.