There are many Dhabas as well as food-chains of Barista, Subway, McDonalds and Café coffee Day along the route to Chandigarh.
After crossing Ambala, head straight on NH-1 instead of going on NH-22 to Chandigarh till you reach the right turn for Kharar as it will save you from traffic congestion on Ambala-Chandigarh highway. But if you want to visit Chandigarh you can take NH-22 which will take you to Zirakpur and then take NH-21 to Chandigarh. It will be an hour drive from Ambala. From Chandigarh you can take NH-21 for Manali.