For some folks the gas pains could last a long time. I would suggest not sleeping on your back flat, either prop yourself up with pillows or sleep in a recliner like I did for almost 2 weeks after I was banded. I remember not feeling "normal" for about 2 weeks and yep... had lots of that shoulder gas.
I returned to work 6 weeks after surgery so I was eating solid foods by then. Bringing your food is the best thing you can do for yourself. At this stage you really don't want to depend on anyplace having the foods you need/can eat. Keep some protien shakes at your desk for emergencies.
Everyone reacts differently to surgery. I know some people who, after band surgery went shopping the next day... wholey crud... I couldn't even sit in my car until day 5. I was hurtin. So you see its really an individual thing.
Good luck to you and good luck at work. Let us know how your doing.
One last thing... Give your doc a call and see what he/she says