Hi Lisa! Both miniature golf options -
Fantasia Gardens and Winter Summerland are really fun ways to spend an hour or so outside of the parks. (And choosing to go in the evening rather than the daytime in August is a great idea!) Both parks are open from 10am - 11pm daily.
The easiest location to get to using Disney transportation will be Winter Summerland, which you simply need to take the Blizzard Beach bus and walk right over from there, as it's right at the entrance to Blizzard Beach. My family absolutely loves Winter Summerland and have been on both sides - Snow and Sand. It's definitely hard to choose a favorite side, the theme is great on both!
Fantasia Gardens does not have any direct transportation from a Disney bus. Instead what you'll need to do is take a bus to Disney's Hollywood Studios, then take the boat to the Walt Disney World Swan, and walk across the road from the Swan hotel. Alternatively, you can take a bus to Downtown Disney, then transfer to a bus heading to the Swan. Obviously that'll be a little longer trip, but it is still doable.
Whichever spot you choose, best of luck for a hole in one!
~Suzannah