i have food allergies (meat, chicken, pork) and i'm lactose intolerant. i just got married in mexico last week and i had no problem finding enough food to eat.
if it is a severe allergy (epi-pen required) she can let them know when she is booking al la carte restaurants and they may have her bring a note with her to the reservation.
at the buffet there should be enough to eat for her without milk as i'm sure this is something she has dealt with long enough to know what foods to avoid.
i prefered eating at the buffets over the al la carte because their was more options for me and i could pick & choose what i wanted.
if you have any more questions feel free to ask me. i'm also a holistic nutritionist.