Lacanau is on the Gironde peninsula, which is probably more than a hundred miles south of the Vendee. Most of the inland side of the Gironde is vineyards - including famous ones - Chateau Rothschild, Margaux, etc. The famous vineyards have tours, but these are generally booked months in advance. There are others that you can just turn up and go round. We had a tour around Chateau Beychevelle (just turned up, but I think we were lucky) but unfortunately the wine was too expensive for us, even so! If you find Lacanau on Google maps, you can use the search facility to see the nearest vineyard and there really are thousands to choose from! Have a look for names you may recognise. I don't know any specific organised tours - but you could probably start by just looking at general websites about the wines of the Gironde like this one
http://www.visitbordeauxgironde.co.uk/Decouverte/LesvinsdeBordeaux/AOC-de-Gironde
How old is your group? Lacanau is a surfer's area, and both my sons go in the summer (late twenties, early thirties) - and Lacanau sounds very much a young person's place from their descriptions of how they spend their time! I can't help with places to go, things to see, because we just did beach and vineyard, Cap Ferret, the Dune de Pyla, the oyster beds of the Arcachon basin, but it's worth a trip to the Dune de Pyla near Arcachon, which is the largest sand dune in the world and taking in the oyster beds whilst you're in the area..
Hope others come along with some idea.