I can find two achievements for Rodd, but they are of Cornwall. I can't see any for Rood. Given that coats of arms belong to the original grantee or user and their male descendants, it may be that you don't actually have a claim to any of these arms. It is a common misconception that arms belong to a surname but they don't.
All you can do is complete your genealogy and hope that you find evidence that one of your ancestors actually bore arms (perhaps there is a record in the Somerset Visitations).