Hi, Spryng, and welcome!
Are you in SAHM with Michelle? She's fabulous!
Yes, you can have couscous in Phase 2 and 3. You need to limit it to a serving at a time, which is 1/2 cup. If you feel you can have 2 or 3 servings a day, try it. Each person is different, so you'll only know if you try. But start out with one and see how you do.
I have never seen WW couscous, but if you can find it, by all means, try it. In the meantime, you can use the regular kind, but the GFGCG lists it as "limited" which we have taken to mean "once a week".