This would depend on what your meal plan is. Check the nutritional information on the frozen dinners you are eating and see if the numbers are acceptable for your own meal plan.

If you're not sure how to do this, it would be good to consult a dietician. Tell the dietician what sorts of frozen dinners you eat and see if they can be worked into the meal plan.

In general, foods you cook yourself are healthier, because even "healthy" frozen dinners tend to be heavy on starch and other "fast carbs" and contain various additives. Home-fixed meals are also a lot, lot cheaper. Then you can use the money you save to buy some expensive but delicious food that you particularly like (as long as it fits within your meal plan).

Why don't you try having a salad with some kind of protein added instead of the frozen dinners. Or prepare meals in bulk yourself, freeze them, and heat them up for lunch.