I work two days a week and DH is full time. You can only do what you can do. On the days I don't work, I don't really get involved as much as I would like as I also have a very active 2.5 DD who would not let me participate effectively. I try and contribute other ways by making sure I help with fundraising (chocolate drives and so on).
When special days or activities come up on days I work, DH and I work around it if we can. Our boys also go to after school care, the number of kids is massive that go now. We are a school of 300 or so kids and the numbers for before and after school care are very high, it just goes to show there are many parents in the same boat.

All kids miss out at some point due to parents working or even if they have a full time stay at home parent, they may not be able to participate in everything, it's a very common occurance these days and something I think kids and schools are used to. There doesn't seem to be as many traditional parenting rolls where one stays home full time and one works full time like when I grew up.

Father's Day is coming up and the my boys school are organising a breakfast and maths games afterwards for the Dads that will finish at 10am. They are trying to help the Dads by making it an early start will a little play and enough time to get to work after.

I know it's hard, I often think am I doing enough.

As for the Disco, what does your DD want to dress up in? Sometimes as parents we can get caught up in the moment and start to stress about what other kids are going to be wearing. Go straight to source, she may well be just as happy and confident in a leotard and carry a hula hoop or swimming costume.

You are doing your best and I bet your DD knows, try not be so hard on yourself.