It works, the English left wing pursues the French, and your Normans swing in from the flank and cut them to ribbons. Soon Harold is left with only his center. The Bretons are busy fighting the English right and you can't go there to help them just yet. It appears that Harold is winning up there, and your Normans are starting to waver again.
Lead an attack with the French wing on Harold's position.
Send the French to mop up the English right and save the Bretons, while you lead your personal troops around to the rear and charge Harold's postion from there.