My experience is the same as Jayney, won't have express milk, breast milk is from mum only. I start working part time when Charly was 10 months, she would BF when dropped her at Granma and then 8 hours later when I picked her up. Made her start eating other things which was great. I was worried at first so brought a pack of the individual formula satches, she drank them with out any problems, the first couple of times when Granma thought she needed extra.

Hope this helps