I'm due in a couple of months with no 2, am determined to do better at breastfeeding than I did with no 1. Would like to give him/her the odd bottle from 6 weeks on or so, I've got an Avent Isis hand pump and used the Avent bottles with no 1, are the Via range any good for expressing and storing breastmilk or should I use the freezer bags (from Boots, etc), or something else entirely???