I agree with this. Apple is quite forgiving. Explain the situation and it's possible (not likely, but possible) that they fix it for free. I know half a dozen people who have had broken iPhone screens fixed for free.
But do as dictoresno suggests, explain what happened and ask to buy AC+ and make an immediate claim, and you may be in luck. Apple also appreciate people being straight-up with them. And if you don't have any luck the first time, book into another store and try again.
Fixing it yourself (difficult with a water resistant device) will also mean that you have no warranty for the remaining warranty period should something else go wrong.