Please do not make your daughter do her First Holy Communion.
If she asks of her own bat, then explain your thinking, and if she still wants to do it for her then cross that bridge when you come to it.
I'm a catechist in the UK, so possibly different to the Dublin ones. The scenario AnnaRose describes doesn't fit with what happens here for the most part.
It's a lot of preparation; that is true. We have the children do a class a month for 10 months. Between times, there's an expectation that they go to mass and learn from the community and their parents. In situations where the grandparent is leading the charge (and this does happen), the grandparent brings the child to church and does the homework with them.
We know which children/families are not interested, and discussions are had with parents about the benefit of waiting a year or two. The priest makes the final decision about whether they may receive the sacrament.
For what it's worth, my children go to a Catholic school in the UK, so there very much IS the choice for the parents who go there. They still don't all do their Communion at exactly the same time as their peers. Given that you are at a school where there's no choice about going, I very much doubt you will be completely alone.