This is the type of cloak worn by warriors in the bayeux tapestry, and by various early period men and women. It is essentially a piece of rectangular wool that is pinned together to keep it on the body. If you have an old blanket, then no sewing is required.
Women and scholarly or elderly men generally wear full length (ie to about the ankles) rectangles pinned at the neck with a pin or "pennanular" (a nappy pin will work, but doesn't look very period - but can be hidden under the cloak). Try using a blanket - apart from some possible pin holes, it can be used as a blanket again, especially on your bed at night during camping events. ifyou cloak is too long, fold the top bit over as a sort of collar, then pin it.
Warriors often wore shorter cloaks (just below the knees), pinned above their right hand shoulder to allow movement of their sword arm. This also works well for women trying to get stuff done.
If you don't have a pin, many pictures show draped fabric rectangles with no kind of fastening. It'll fall off unless you sit or hold it in place, but i'm told by someone who wore a blanket for 3 days this way, that it works quite well.
This cloak has no hood, but you can pin it more loosely and drag a fold of the cloak up over your head as a hood.
A rectangular, belted cloak forms the early basis of the Scottish Great-Kilt. The women's Earisaid (pronounced "air-sitch" and spelt in a multitude of variations) is a good example of this and still worn in this fashion.