Here's an idea to come to Hammamet :
The city of Hammamet is 60 km from Tunis.
Once arrived at the airport Tunis Carthage:
1) You can take a taxi to Tunis train station (about 5km from the airport) to take the train to Bir Bou Rekba (http://www.sncft.com.tn/) then a taxi up to the Hotel Mehari Hammamet Yasmine (All 10 euro).
2) There is a second way to go to Hammamet, you can take a taxi to " Hammamet Louage station" named Bab Alioua. There are some big cars (for 8 persons) that make the travel Tunis-Hammamet, you can find such cars at each time (about 3 Euros).
3) You can take a tourist Taxi from the airport directly to the hotel (20 euros)