I've not been in the Lot for a couple of years but found it easy enough to fill with Oli. I've stayed in the apartments across the road at André's. Oli manages these.
The conditions aren't always great in the Lot so it's good to have a bad weather option - e.g. sidemount kit for the smaller caves. I wouldn't go in the heat of the summer as it's crowded and cave conditions might not be the best.
Other than that, it's easy to find your way around. There are a few books available and Oli has a map of dive sites on his website: https://www.thecavetobe.com/en/dive-places
Gas is pricey, though, so take as much you can!
I've not been to France for a very long time - The Lot is great offering some spectacular diving. NDY offers some excellent advice up above and he has very extensive knowledge well worth tapping into.
I've only been once (but heading back soon) and if you want an easy dive trip then Harald is a good place to stay - although probably quite a pricey option now. We are just taking compressors and hiring a house this time around.
Interesting to read this again after about 6+ years...