If you are flying from interstate and are only visiting Tassie for the wedding, we suggest flying in and out of Launceston rather than Hobart. It is half the distance from the venue.
If you want to limit driving - there are flights on Qantas and Rex which go from Melbourne directly to Wynyard (also known as Burnie Airport (BWT) - they are the same and are located in Wynyard not Burnie). The planes are very small, you will likely have restrictions on weight and fares are reasonably expensive, but this airport is the closest to the venue.
If you are planning on staying and having a look around the Apple Isle, you may wish to fly into Launceston and fly out of Hobart or vice versa. Just be sure to check what works with your travels, as the airports are nearly 3 hours of difference in driving distances.
Hire car - you will need one. There is very minimal public transport between Launceston and the venue or elsewhere in Tasmania. Given the amount of space available at the venue, campers, vans and trailers would be an ideal option to kill two birds with one stone in terms of accommodation and transportation!
Hobart: 340km (4.5hrs)
Launceston: 180km (2.15hr)
Burnie: 35km (35min)
Wynyard: 15km (15min)
Sisters Beach: 5km (6min)
Boat Harbour: 3.5km (4min)
This website has private short term rentals of camper vans from Launceston and the surrounding areas if you are interested in having both somewhere to sleep and something to drive!
This links to the rental car options available at Launceston Airport