Ah I know this feeling. My daughter has caught soooo many bugs, one after another, since starting nursery. However, unfortunately your manager would have a case against you if you keep taking time off. They can say that you aren’t able to do the role. I’ve had to use annual leave and dependency days to cover sickness so far, in the worst case I’d have to use unpaid leave.
Whilst many work policies will be flexible in emergencies, my work for example will say, you can use annual leave or unpaid leave to cover it, and should it keep happening, that’s something they can raise as an attendance concern. I don’t think being sacked is the first step, and hopefully if you explain it’s bug season but you have no other options, and get through winter they’ll be understanding. You may need to come up with a plan for how those days are covered though, and what a concerning threshold might look like for your manager.
I think if I were you, I'd request a union representative to attend that meeting with me
Depending on what she says in the meeting depends on what you should do. If she threatens you with being fired for having to look after your child then calmly explain to her that if she does that you will be taking the matter further and possibly suing for unfair dismissal where you would get quite a decent pay out and she would probably lose her job.