My head would let teachers/TAs with children in our school pop to the hall and watch plays/nativities/concerts, but not if the children were in a different school. I missed virtually all of my children’s Christmas plays.
It's swings and roundabouts though isn't it? Teaching is well-known for being extremely inflexible during term time when it comes to time off, so from that point of view isn't family-friendly. But on the other hand obviously teachers get a lot more time off for school holiday times and therefore can spend longer with their children at that time and don't have to find weeks and weeks of expensive holiday childcare.
There are advantages and disadvantages either way.
Our Head allows this. It’s unpaid and usually only a half day is given but she tries to be as flexible as possible. She says if we needed a meeting with a parent in the school day or a child at our school had a big event (we’re secondary so not a nativity but perhaps a performance or prize ceremony) we would want the parent to attend and, if necessary, take time out from work so she allows our teachers to go to things for their children.
Out of 4 schools (secondary), I've worked in one that allowed this, 3 that didn't, so it's worth asking. Although I did work in one horrible school, where daring to ask would have meant a sudden "support" plan put in place!
We allow all our teachers and support staff to go and watch their children in assemblies, shows etc. It's paid too - they are only out for an hour / hour and a half or so and it's important. You never get those times back!
I’m a HT and I would bend over backwards to accommodate a request like this- everybody should see their child’s Nativity. Go to your HT with a plan for how you can be covered and don’t leave finding the solution up to them. This will go down well!