Do not scratch, apply lots of moisturiser, soaking in cold water out of the sun will help to sooth. Expect to look like a cooked lobster and peel off lots of skin in the coming days. Once you are "peeling" STAY OUT OF THE SUN as the "fresh" skin will be more susceptible to burning.
Once you are over this apply bucket loads of sunscreen, wear a broad brimmed hat (you don't really need corks dangling from it) and cover your skin when ever possible. Avoid midday sun.
Hope you enjoy your time here.