Although most theme parks will have their own policy on extending military discounts to Allied nations, the Morale Welfare and Recreation (MWR) center at the US Navy facility in Orlando will allow UK and other Allied military members access with their nation's military ID card and/or NATO Travel Orders. At the MWR center, service members can purchase deeply discounted theme park tickets such as Disney, Universal Studios, and Sea World.
So bypass the system as above - always a way........