Périgueux is one of the great food towns of south-west France. The local trinity — duck, walnut and truffle — turns up on most menus, sometimes all three on the same plate. Walk the streets around the cathedral and you will find a tight cluster of small bistros and proper restaurants, most with a fixed-price lunch menu under 25 euros.
For self-catering and picnic supplies, the Saturday market at place du Coderc and place de la Clautre is the obvious stop. The covered hall is open most mornings the rest of the week.