Either take the boat from MGM or walk to Epcat's International Gateway entrance. Once you are in the park, turn left. UK will be the first country and then you will see Canada. Le Cellier is easy to find.
I have never had to switch boats. It took about 30 minutes though to go from MGM to Epcot. You have to stop at all the Epcot resorts (Swan/Dolfin, BW, BC/YC) first, and then you get to Epcot. It was a nice little break for us, but the walk is not bad.