1) Get to Rome (central "termini" station)

2) Take a train to Orbetello station: from Rome it takes 1h20 to 1h50

3) Take the bus from Orbetello to Porto Santo Stefano: it is frequent and takes 20min.

4) Take the ferry (two companies: maregiglio and toremar) from Porto Santo Stefano to Giglio Porto (on the Island): it takes 1hour

5) Take a 5 minutes bus/taxi ride (or 20 minutes walk) from Giglio Porto to Hotel Arenella

Follow this link for a list of possible connections (train+ferry) with departure times and complete timetables

Below find an interactive map with explained directions (zoom and click on routes/arrows)

View Workshop Directions in a larger map