If you have celiac disease, I would stick to gluten-free oats. At least in the U.S., ALL regular oats are processed with wheat, on the same equipment and are contaminated through and through with gluten. It can make you pretty sick, and even if you don't see symptoms, they will set off the autoimmune response. Trace amounts can be poisonous for celiacs.

If you keep gluten free for some other reason than celiac, it may not matter.

There are some decent gluten-free whole grain breads out there as well; Udi's and Canyon Bakehouse are two. Buckwheat is another good brown. And there may be some cold cereals; I use Rice Chex and Corn Chex now and then. There is some sugar in them which you won't want if you have detoxed, but they work well enough in the earlier steps.