Yes, it is easy to get to - and I do think it's worth it. Maybe after roasting marshmallows, you can take a wagon ride at the Settlement, that is also a favorite thing for me to do at FW!
You can walk to FW in about 20 minutes from the WL. You can also get a bus, or a boat. (I'd not walk after dark). That takes you to the Settlement, which is a short bus ride (or about an 8 - 10 minute walk) from the Meadows, which is where the campfire is.
My FW photos are on page 2 now, but I show the walk between FW and the WL, as well as to the meadows. Again, you may end up taking a bus or boat - but either way, it's not too far.
http://www.denisesfitnessblog.com/disney/?pg=2
The Smore kits aren't cheap at Disney - the sticks are at least, but I brought my own marshmallows, chocolate and graham crackers last time.

But it may be easier for you just to buy it there.