Pumping milk on a break?

I'm going to go back to work part time. I've seen so many jobs that I could be doing, and I'm thinking I may end up working 4 hrs. a day. I don't know yet how many days I will be working, and I'm not sure what kind of breaks I will be getting. I'm going to ume that I will probably get a 15 min break at least. I'm not going to make a big fuss out of them having somewhere for me to pump, since it is only for a few hours, and I need the money. I can go out to my car if I have to, and snack on something at the same time. But does this sound reasonable?? I mean, I'm going to feed my baby before I leave for work of course, and I'd only ber away from her for probably 4 1/2 hours. She usually eats every 2 hrs or so, so this sounds like it could work for me. I'm not quite ready to go back to work full time just yet, but I really can't afford to sit around and not work either.