Running searches hasn't done me well, perhaps because I don't know the proper terms?

I am considering buying a bolt of fabric, tartan in the colors of Muir and maybe MacWhirter (partner's heritage).
Are there special terms for going about this?
I don't see these fabrics at shops (googled) so I am guessing I have to request they be made?
Would anyone here happen to know how to describe the Muir weave? MacWhirter?
Would hate to order a bolt and find out that's not what it is in a US fabric shop, but something entirely not what I needed.

Confused now but hopefully learning, and retaining (well, old age, hard to retain things now days).