Where are the best places to visit in Cornwall, England?

We’ll be taking the train as we don’t drive, and we’re thinking of packing a tent, as we’re pretty broke. I like beaches, she likes villages and seafood restaurants. Oh, and we have a two-year-old in tow. Basically looking for some basic information on the best spots, hidden treasures, and preferably within a short taxi ride from a train station. Thanks.