I am lucky in I tell my boss I wont be in til late or I leave early or something due to school sports days (but they tend to do Twilight Sports), any day concerts etc, I attend about 90% of them & ikf I am not there, then my Mum makes sure she is or DH does!
They do organise a lot of Family things after school hours & I must sya the Sports nights are funny, almost all the families know each other & sit around cheering loudly, eating a BBQ & drinking!!! It's quite enjoyable....

I refuse to ask permission to attend my kids activities, I simply say I will be late or leave early depending on the time, I have always said my kids come first & if work dont like it sack me....!