you cannot copyright (or patent) an idea. You can patent a product, or an industrial process (although it's not easy in either case) and of course all 'original work' is protected by copyright automatically. Original work may be a painting, a photographic image, a magazine article, a song, a piece of music, a play, sculpture etc., but not an idea or concept.
If you are so certain that your idea is a winner why don't you design and publish a website? When it's finished, copy it onto a CD, and print each page. Then, put the copies into an envelope and post them to yourself by special delivery. Keep the unopened envelope in a safe place. That gives you a time capsule with a verifiable date, and that would at least demonstrate that you did have the idea. It won't stop someone copying your concept however, and that is something that happens(quite legally)all the time. It will help you protect any key text or images though, and sometimes that can be very useful.
I don't want to dampen your enthusiasm, but many people have that Eureka! moment, only to find that the concept won't work, or that someone else has thought of it before. There's only one way to find out however, and that's to give it a go. You say you haven't the time or the patience to do this, but that surprises me - if it's such a good idea isn't it worth finding the time? You might kick yourself when someone else does it.