This is worth a read: https://www.coeliac.org.uk/gluten-free-diet-and-lifestyle/food-shopping/law-on-gluten-free/
Last time we tested Huel is was 17 ppm, which is official gluten free, but the gluten in oats varies from field to field so it’s very difficult to confirm that will always be the case, so we are planning to blend a version of Huel using gluten free oats.