Hi there, Jennifer!
Thank you so much for the kind words; I hope I'm able to help you out!
Disney's BoardWalk Inn is definitely accessible from
Epcot. However, you'd need to get from the main gate to the turnstiles in World Showcase - the International Gateway.
The BoardWalk and Epcot are all connected via the "Friendship" ferries. There is also a nice wide walking path that follows a similar route.
Whether you choose to walk or boat, you will enter Epcot through its full-service back entrance, the International Gateway, located between the United Kingdom and France pavilions in World Showcase.
Unfortunately, there is no way to get from the main gate to the International Gateway without a Park ticket. Your best bet, I think, will be the bus system.
Have a wonderful time!
See you later, celebrator,
-Deborah B.