Cognac is a 45 minute drive from Montemboeuf. There is a very scenic route that you can take through the vines. The étapes du cognac is a well marked driving route.
Most of the Chateaux are closed during the winter, so it is always worth checking the opening times before you leave. You should also book ahead, because they are popular. Tours of the houses are a regular thing and most of them do offer in both French and English. Some that you might like to try are;
Camus – Create your own Cognac blend of Cognac on this tour. www.camus.fr
Hennessy – This tour includes a boat ride across the river. www.hennessy.com
Martell – One of the oldest of the Cognac houses, founded in 1715. www.martell.com
Baron Otard – Tour includes a look at the castle home of French King, Francois I www.otard.com
Remy Martin – Started in 1724 www.remymartin.com
Meukow – Fantastic tour and they just launched a beautiful new restaurant as well www.meukowcognac.com