Yes, Fantasia Gardens is within walking distance from the BW.
I'm not really sure what you're looking to do at the BW...are you staying there and hoping for a few diversions at your resort, or planning to visit for an evening? Either way, I think it will work out fine.
There are a few games, some picture booths like they have in arcades at real boardwalks, and various places and things to eat. Ice cream can be purchased at the sweet shop and there's also the bakery for desserts...plus several restaurants. There is also live entertainment most evenings. We've seen a man playing a rolling piano, a jazz band, a magician, and I think, a juggler. There are also some shops, but they're mainly the typical resort stores.