I am tempted to leave the thing "unprotected" - can't really visualise flocks of baddies converging on a tiny coastal village to snatch a few minutes of free airtime. Any way there is another site (unprotected) for a local amenity which might appear to be a better target!
Dear oh dear......
(1) Many opportunities for man in the middle attacks against you and people getting hold of your authentication credentials for online banking and other secure activities you would rather they would not.
(2) It only takes a few minutes of someone downloading kiddy porn via your internet connection for you to find yourself in a whole host of legal trouble. Sure you may be innocent..... but do you really want to loose hours and days of your life explaining that to the authorities ?
Don't be lazy. Setup WPA2 AES .... its not that difficult.