Hello
My 2 year old son has a true milk allergy so we avoid all dairy and egg products. We have visited Tenerife (self catering) and Rhodes (Half board). We found products easy to come by and everyone we came in contact with (shops,restaurants,cafes etc) really helpful and happy to accomodate us.
I took lots of his favourite treats with us and his soya milk (just incase).
We dont even think about his allergy-our only trouble is where can we book for next year!
Hope you find somewhere and i'm sure you will have a great time.
Luv em xx