I have coeliac desease and it is incredibly hard to find places safe enough to eat at, but wagamama is the best restaurant I have been to in terms of customer service and dealing with allergies. They allow only the manager to take the order for any allergens, and your food then gets prepared seperatly and by the head chef to avoid any cross-contamination, I have never seen any restaurant go this far to keep their customers safe, so I would definitely recommend this for any allergen.
As well as the great customer service, I have never been disappointed by any of the dishes I have had there, they are always well presented and delicious, really an amazing restaurant.