Hi Iam breastfeeding my boy and also with solids, if I go to work back do my boy can feed on expressed milk stored and kept in bottles?

A Simple Guide to Storing Breast Milk While You Are Away from Your Baby read this article

Yes you can express and store milk in baby bottles steel containers or milk bags. Remember to store in refrigerator of longer than 4 hours. And if longer than forty eight hours then in the freezer.