Hi Stuart, welcome to the world of Scottish clans. Maria has referred you to the McCulloch/MacCulloch tartans.
HOWEVER there is a much held misunderstanding that a Scottish name and even a Highland Scottish name must belong to a clan. This is far from the truth. Pre-1746 there were very few clans and lots of Lowland families. Since 1822 many of these Lowland families have started calling themselves clans even though pre-1746 they would probably have cut your throat for daring to do so!
Today a reasonable definition of a Scottish clan is a family name recognised by the Lord Lyon as being a distinct family grouping for which he recognises that an individual is or may be "first of the name". The "bible" on the matter is the Scottish Clan And Family Encyclopaedia by George Way of Plean and Romilly Squire. It lists all the recognised clans and Armigerous families.
My reading of the entry for McCulloch is that it is an Armigerous family i.e. individual members of branches of the family have been the holders of coats of arms but no chiefly family is presently recognised.