Originally Posted by Tothill

I doubt there are bolt boards, as the fabric is folded flat in shops.

OP, I am not sure if you have access to a large quilting ruler or a thin board that is 6x24 inches? Open your fabric on a table. When you get to one cut end, wrap it around the ruler or thin board until you get to the other cut end. Slide the ruler out. You can at this point fold the fabric so the short ends meet. Or leave it in a long thin rectangle.

The technique is called ruler folding.

You can find YouTube videos showing this technique.