I would recommend you avoid the microwavable dinners and also avoid any processed food/meet since the meat quality is low. Processed food also have a lot of additives and salt added to make it taste better.
But it comes with the side effect that it is no longer really healthy to eat, it will actually as another poster said throw your macros off the charts.
If you don't have space for a real stove at your place, you should be able to use something like this :
https://www.amazon.com/dp/B01MYGMO6M/?tag=neogaf0e-20
That is as small as you can get them, but they run on Butane so they are somewhat costly to use as your everyday stove replacement.
Butane is IMHO good for occasional use, when you are out camping or similar, but not for permanent use.
If you want something that is economical you can cook with every day, I would switch to a portable stove running off a Propane cylinder instead. But then the stoves are often a lot bigger.
This one is one of the smallest ones I have seen :
https://www.amazon.com/dp/B0009JXYQ4/?tag=neogaf0e-20
but then you have to take into account you also need the big propane cylinder.
Those are the gas options I would consider. Portable gas stoves have the additional benefit in being portable, so that if/when you travel somewhere you can bring it with you.
You also have electrical stove tops such as this :
https://www.amazon.com/dp/B01IA3H8QM/?tag=neogaf0e-20
I wouln't get one of those since they are not really that portable (you can not use them unless you have access to elictricity) so I don't see the point in them.
The items above are only examples. I am sure you can get similar products in your local hardware stores as an alternative to Amazon.
I would recommend getting something similar to the Propane stove above if you have a balcony or an outdoor area you can cook in. You should not use butane/propane portable stoves indoors.
For pure indoor use maybe the electric stove top is the best.