@chickencuddle, as I said in my earlier post, I've been in abusive relationship too and I know how painfully difficult it can be to leave. If you're not ready to go, that's one thing. No one here can judge you for it. But you owe it to yourself and your children to be honest about the situation.
He isn't being great. If he were, you wouldn't need to check that your reactions are reasonable with strangers on the Internet. If he were, you wouldn't be waiting for the next cruel thing and worrying what it might be. These seemingly uneventful periods are actually PART of the abuse, not a break from it, because they contribute to this horrible gut-wrenching uncertainty. Abusive behaviour always generates doubt and fear. And I say 'seemingly uneventful' because he's still doing bad things. You're just convincing yourself that they're not that bad. He kicked the dog, but it wasn't hard, and it couldn't have hurt, and he's a gentle vegan with animals really, and the dog still got on his lap...and so it goes on.
Your kids will pick up on your anxiety and stress. This is where you really are being unfair. You want to believe that they're not scared or hurt or even aware of the situation because that's a comforting belief for you, but kids aren't stupid. They're in the same environment you are in and it's not any nicer for you than it is for them.
Your partner already has equal access to the kids. Your belief that you can make sure he never goes too far is a common belief among traumatised women who desperately want to feel they have some control over their situation, but his behaviour over the kick is showing you that actually you don't have that control. He's already succeeded in convincing you that kicking the dog wasn't that bad. You keep saying you'll leave if he does X and Y, but he already has done X and Y, and you chose to stay with him. He's pulling all the strings here, and he knows it.
Women's Aid were ready to help you fight your corner, as I remember. You might not be ready to accept that help, and I sympathise, but at least stop trying to convince yourself that this is a successful game of happy families.