Driving from Toulouse 

The shortest and most of the time fastest route is over Moissac. This is 134 KM. Driving time is under 2 hours (1 h 54 min from the airport according to Google. We do it in less without speeding!) 
Once passed Moissac, the road is very picturesque and quiet.

Complete driving directions from the airport on Google maps.

 

If you are not in a hurry, consider a stop in Moissac. You can visit the world famous Abbey Saint Pierre and the Cathedral. There are nice restaurants on the square in front of the cathedral. A bit out of town there is a canal bridge over the Tarn. This is one of these bridges where you can see boats crossing on the bridge, while standing along the river under it! If you are interested in engineering archeology, you must see the "Pente d'eau" of Montech just a few miles south of Moissac.