we have flown to usa,about 3 years ago and a internal flight and had no problems, we brought our own food.
we are planning to go to florida this summer, and are taking extra , extra safe food , in case of strikes, volcano ash, etc!
we also went to spain on ryan air, which was ok, and ferry/car to france , italy.
we have always done a fair amount of self cattering, and eating out.
for flying , got every med with a prescription label, and note from doc.
son carried his own meds, i carried spare set.
a letter from his gp in his meds, explaining that he must carry them at all times.
extra health insurance arranged before we go on flight/hols
medic alert bracelet worn by son.
did have a slight problem with with liquid piriton, son had to drink a bit before boarding to prove it was safe ....