I wouldn't use tar and chip as it is not as effective as asphalt/macadam and will look out of place. There is a product available in small sealed buckets which will do the job. It's a macadam product that is used for small repairs. Local Authorities use it for emergency pot hole repairs. Once it sets its like concrete. I'm not sure where you might purchase it. If google the company "Irish Tar " they might help.