Coq au vin is traditionally made with a one-year-old cockerel - full flavoured and perfect for the stew pot.  If you can get a real coq, brilliant (a few good butchers supply them - in London try the Ginger Pig, delivered to your door by Hubbub).  Otherwise use the legs of regular chickens - one per person.  Legs have more flavour than breasts, and are more suited to slow cooking.

To get 10 pieces from the bird:  Cut out the spine and save for stock.  Take the legs off and divide into thighs and drumsticks.  Take the wings off, remove the wingtips and save them for stock.  Remove the breast plate and cut the breast in half, then divide each breast piece into two.  You should have 10 pieces.  Or ask your butcher to do it.