Most people who visit Ireland head straight for Dublin or Galway, said Andrea Bussell in National Geographic. Even some locals aren’t familiar with the “great green valley that stretches through County Tipperary” in the heart of the country’s “Ancient East”. But, tucked between the Galtee Mountains and a “forest-clad sandstone ride known as Slievenamuck”, the Glen of Aherlow is the perfect place for a “slower, nature-centric” holiday. Here, “tal…