This is what the current UK Government travel advice is:
The Foreign and Commonwealth Office (FCO) advise against all travel to:
the Chaambi Mountain National Park area
the Tunisia-Algeria border crossing points at Ghardimaou, Hazoua and Sakiet Sidi Youssef
the militarized zone south of, but not including, the towns of El Borma and Dhehiba
within 5km of the Libya border area from north of Dhehiba up to but not including the Ras Ajdir border crossing
The FCO advise against all but essential travel to:
areas south of, and including, the towns of Nefta, Douz, Médenine, Zarzis (including the Tunisia-Libya border crossing point at Ras Ajdir)
within 30km of the border with Algeria south of, and including, the town of Jendouba (this area includes the archaeological sites of Bulla Regia and Chemtou)
the governorate of Kasserine, including the town of Sbeitla
If you travel to the interior of Tunisia, you should do so with a reputable tour guide.
There is a high threat from terrorism, including kidnapping. Attacks could be indiscriminate, including in places visited by foreigners
Make your own mind up! Cornwall it is then...