Huel uses standard oat (not gluten free oats) which are officially iclassed as an allergen.
This is the same for all products that contain oats apart from the ones which are specified as gluten free. There are not other allergens in Huel - as laid out by the https://www.food.gov.uk/science/allergy-intolerance/label/labelling-changes
Having said that we also add the warning that Huel is made in environment that also handles nuts, peanuts and eggs.
I hope that answers your question.