Istanbul to Athens by train

We are an Australian couple in our 60's, thinking we might take
the train from Istanbul to Athens with a two day stop in Salonica.
With English our only language, no familiarity with either Greek
or Turkish cultures and tending to be nervous travellers, we
wonder if we would find this excursion difficult.
Comments from people who have already had the experience would be
greatly appreciated.

Graham Robbins
Brisbane, Australia