Gargy, I did many of the same things in my pg I have a book that I used as my bible during pg it answers most of your questions my SIL has it at the moment but now her little 9lbs80z bundle has arrived I'll get it back of her and pm you the details (got it in Angus and Robertson.)
I know it's not good to eat certain foods but I'm sure a little slip ossaisionally won't hurt, I did manage to give up deli meats and soft cheeses but I had a cheese craving at one point and found out the hard way why it's not good to eat to much cheddar!!! I also craved red wine but the funny thing was that I let myself have a small sip only to find out that it tasted repulsive to me now.
I didn't have too much trouble avoiding food as I had just enough morning sickness to limit my interest in food quite a lot. I don't see that taking lunch to work would be bad if as you say it is in a cooler bag.
I certainly took meals to work during my pg, check out a pregnancy thread and ask your question I'm sure the girls there will have some answers for you or maybe even Allan?