You can now, thanks to Easyjet fly from London to Tours. The airport is small so very simple. Hire a car and drive on the motorway A28 directly to the château. It will only take you from Tours 1hour and 15 minutes.
You can also take the train from St Pancras International station and arrive in Le Mans without going through Paris. Le Mans is just 30 minutes from Saint Paterne.
Alençon Sud exit N° 19, follow the sign to Saint Paterne, Saint Paterne centre, and at the 2nd stop turn immediately on your right.
From Paris : take the " pont de Saint Cloud ", then the motorway A13 in direction of Versailles, and then the N12 in direction of Dreux, Verneuil sur Avre, Mortagne au Perche and finally Alençon.
From Alençon : take the D311 in direction of Chartres/Mamers/Orléans. At the exit of Alençon, the alley of the château will be on your right, opposite a gas station, in the centre of the village of Saint Paterne.
Take the A1 in direction of Paris. Stay in the right hand lane, and follow the signs " Paris Ouest " up to Porte de la Chapelle.
Take then the " périphérique Ouest ". Paris is on your left. Follow the signs for Rouen (the A13 motorway). Continue to follow the direction of Rouen and take the tunnel of " Saint Cloud ". Continue on the A13 until Versailles, and then the N12 in direction of Dreux and Alençon.