R.D.
Pumped milk can be stored at room temp for 6-8 hours (not just 4-6). I would guess if you warmed it and had it 4-6 hours later it would be fine. If you can pump before you leave, it should be okay until baby eats.
Good websites to research:
La Leche League: http://www.llli.org/nb.html
KellyMom: http://www.kellymom.com/bf/index.html
WomensHealth.gov: http://www.womenshealth.gov/breastfeeding/
If you are with your baby while away from home, I encourage you to nurse instead of giving a bottle. There are ways to do it so nothing shows.
Congratulations and Blessings to You!! {Beautiful Baby!!}