Can someone help me with my grammar?!?

I'm writing my personal statement and I've written "school's athletics team" but a blue line has appeared under the "athletics" telling me to correct it to "athletic". To me though, "school's athletic team" doesn't sound right. Same with "Welsh School's Athletics competition". Which is right, "athletics" or "athletic"? Silly question I know but it would be great if someone could help me out!