School lunch

I'm having little bit problems with logging my school lunch. Our school offers free school lunch which includes warm meal (potato, rice or pasta with sauces or warm soups), salad, bread (usually rye bread or crackers) and drinks (I take 2 dl of skimmed milk and 2 dl of water). My problem comes with logging the warm meal, they usually have stuff I have no clue about what it could be in calories. Stuff like sauces and soups are the biggest problem. Good example is kebab sauce, it has some kind of tomato sauce but it's very mild tasting for tomato sauce so it has something else in it too. It also tastes little greasy and has kebab slices in it. I can't find food equal to that from database and I have no clue of its calories. Other example is some kind of oven dish/sauce with salmon and cod mixed in it, it has cream in it and bits of both fishes and some kind of cheese. I cant find stuff equal to this one either and I can't tell how much there's fish on my plate since it's in so little bits and covered in sauce. So I'm eyeballing everything I'm taking and guessing amounts and estimating it little bit too high everytime since I'm not sure how much am I taking and I tend to guess amounts too small.

What would be a good way to deal with this? Or if I skip school lunch what should I take to school with me (no chance to keep it in cold, 3,5 hours in backpack)? My logging is good otherwise but it feels like estimating my school lunch makes it difficult and sometimes I get more calories than I thought I will which messes rest of my day, I have harder time in evenings to eat light meals and my exercises are in evenings so I need enough calories for one proper meal and small snack like slice of bread or fruit there.