Here is a link to a site that has many different fabrics in the Colquhoun tartan. I am not recommending any of these or the retailer, but offering the choices.
https://www.scotweb.co.uk/tartan/Colquhoun-/31928

The information in the other posts are worth reading and taking into account when purchasing fabric for a quality product. Good luck and please let us know what decision you make.