Hey Julia
Sounds like you're in for a great trip later this month. If you're staying in Melbourne and looking for some hiking and beaching, I suggest you hire a car or jump on a V Line Train and head down the coast to any of Torquay, Lorne or Apollo Bay. These three are popular holiday-making spots for locals because of their great beaches, activities and coastal town atmosphere. Lorne in particular has some romantic getaway options, such as day spas and vineyards to visit. We're expecting a hotter than usual March so hopefully you can get in some good beach time.
Within the general area, you can also hike to Erskine Falls (about a 15km return hike from the car park) or visit Cora Lynn Cascades instead (4km return). I would definitely recommend a visit to the Great Otway National Park (a bit further west) - there's waterfalls to visit and a canopy trail.
V Line's website is here: https://www.vline.com.au/
Visit the Great Ocean Road website for details on the region: http://www.visitgreatoceanroad.org.au/
Hope that helps!
