In order to get to the DVC Beach House, you will need to pass through the manned gate at the plantation (Palmetto Dunes?). They won't allow cars that don't have either a plantation car pass (as issued by the resort) or those who are checking in that day to one of the resorts with a check-in site inside the gate. Some plantation resorts or complexes have a check-in site outside the plantation for this reason.
If you are staying inside Palmetto Dunes Plantation, there is another simple plantation (dirt) parking lot where you would have beach access with free parking and basic rest room facilities. It's not far from the Beach House actually. The gate attendent can tell you where to drive.
That week will be jammed at any unrestricted or limited access beach parking site so get there very early (or fairly late in the day) to find parking or ride bicycles to the beach. Have a fun trip.