Hi Graham,
It is certainly possible to get the medications in Vietnam.
Your options are Sofosbuvir+Daclatasvir or Sofosbuvir+Velpatasvir +/- Ribavirin for 12-24 weeks.
Exactly what and for how long depends on your level of fibrosis, how much you can afford, and if you want to avoid Ribavirin (longer treatment can allow this).
Your level of fibrosis is important to know. Ideally from a fibroscan, but failing that Platelets from a FBC and AST from the liver panel give a good enough estimate.