School Uniforms for non-pupils

I am going to a fancy dress party New Years Eve and have a skirt and blouse, but wanted to wear the tie of the school DH went to (as a friendly rivalry with a friend)... I've looked on their website to see where they suggest to buy the uniform and the tie and socks are only available at the school not through one of the uniform stores.  Does anyone know if the school will sell these things to me if I am not a student?

I'm feeling a little embarrased to just call and ask

I don't see why not, especially if you say it's for an old boy of the school.