Wellington's plan was to distribute troops along the whole of Soult's line but make his main attack in the centre. Any breakthrough in the centre or the French left flank would enable the British to cut off the French right flank.
Wellington intended to position his forces along Soult's entire defensive perimeter and focus his primary attack on the central sector. If the British were able to break through the center or the French left wing, they could cut off the French right wing.