travel from Rome to Sorrento

Take the train Rome to Naples; walk to the lower level of the train station and take the Circumvesuviana train to Sorrento. You will need to buy a ticket for the second train. Signs in the Naples train station indicate where to go to catch the train to Sorrento. The same train will stop in Pompeii and other towns along the way.

Alternatively you could catch a bus. The Curreri service leaves Rome Tiburtina station at 2pm on Mon-Sat arriving at Sorrento station 5.30pm

http://www.curreriviaggi.it/

The two Marozzi services leave Tiburtina station at;

7am arriving 10.45am, and

3pm arriving 7pm

both run Mon - Sat. The site has no English version.

http://www.marozzivt.it/web.aspx

Not used either of them but reviews are favourable.