Hi Sharon,
I am Pauline I have a daughter age'd 9 and a son age'd 7, ttc number 3.
I have never been to Greece but if is anything like Spain/Majorca, lots of the restaurants will have childrens menus with things like pasta, rice, chips, sausages etc. As long as your little one is ok with food like this it should be fine.
Lots of high factor suncream, wide brimmed hat and lots of fluids.In Majorca saw a couple of people with small beach tents, just big enough to sit in, encase the sun gets too much. They also sell the all in one swim suits with added sun protection.
For the flight some small toys maybe a couple of new ones that your little one has not seen before if you can stretch to that or something they haven't played with in a while so it is a bit of a novelty.
Hope this helps.
Pauline x