What a great idea for a vacation. But, I notice that all the mentions are of the Canal du Midi - although I love the Midi, are there other canals just as nice? Did you choose the Canal du Midi for a specific boating reason - better locks or something? Or, because that's a region that you want to visit? And, why did you choose the outfitter (if that's the term) that you did? Sorry for the questions, but I think that a seed has been planted here for a future vacation!
Have fun!

Ten years ago we did a trip on the canal de Bourgogne from St. Florentin to Monbard. I chose it because it was one of the one-way itineraries that passed by a greater number of "old stones". We went through 50+ locks in a week. Only one person one the two boats had some experience with boats. We had no problems, even if at the beginning we were weaving from shore to shore like drunken sailors. We used Rive de France.

We have used Locaboat in the Alsace-Lorraine area (canal de la Marne) and were among lots of Crown Blue rentals. Locaboat seemed to have more of the traditional "pénichette" style boats and Crown Blue had more of the Fly Bridge styles.

We have driven along the Canal du Midi from Toulouse to Carcassone (as feasible) with the intent of doing the Canal du Midi next time. Just be forewarned that the water is a sort of murky brown (just in case you were envisioning clear azur-blue!)

These companies have manuals that you can order in advance or purchase at the time you pick up the boat. Other resource material: "Through the French Canals" by Philip Bristow, revised by David Jefferson (in it's 10th edition). And there is a Californian couple (sorry-don't have access to my library at the moment) who has written a guide book specifically for the Canal du Midi, rich with little do's & don'ts and what days the markets are where, what to order at which restaurant, etc. They own a pénichette that they keep year-round in Le Midi.

Definitely rent at least 2 bikes! They are fun and are a great way to get those fresh croissant/pain au chocolat every morning.

Whatever the color of the water in the canal, you do not want to swim in it. On our boat, the wastes from the head were ground up and went directly into the canal. We looked for a tank that would be drained and found none.

crownblueline.com
We rented the Tasman in 2001 and loved it.

Our group chose 2 Crowne Blue lines "Classiques". We chose the Canal du Central... cuisine and wine.