Hi,
We took both our kids to Corfu as babies (now 5 and 7 yrs). May is a lovely time to go. We found that nappies, milk and baby food supplies were very limited in the small resorts. Luckily we had been told this before and took our own. Nappies are also much more expensive in Corfu.
Look for low sodium content (Na) on bottled water, as some brands are quite salty.
It's best to take a travel cot too.
HTH
Lisa.