Then it will probably need a BE marking. There are several AE choices, in several possible combinations, but as far as I know 'ready meal' isn't one of them.
As AE alternatives I would suggestready-to-eat ...
... entree / main dish
... vegetable / side dish
Or if it's a frozen one-person meal,frozen dinner
(possibly now dated)
'Convenience food(s)' is probably what the entire category is called within the supermarket or food-service industry. But you wouldn't say that when you're going to the grocery to buy one.
In yet another parallel thread,related discussion: Fertiggericht - ready meal
That also sounds more or less okay, but maybe more for something in a box off the shelf, not either refrigerated or frozen.
Actually I'm not sure what we call the whole category in boxes that you have to add something to, like ground meat (Hamburger Helper) or milk or butter (macaroni & cheese, cake mix). Those are also convenience foods, but not ready-to-serve.
And here's another threadrelated discussion: Er ernährte sich von billigen Fertiggerichte...
that helps confirm 'TV dinner' for AE. I guess if it's dated, it's no more dated than dude and WK and I are.
('Instant,' by the way, doesn't work for this; in AE it's only for things that come in powdered form to which you add water, like instant tea or instant coffee. Sometimes instant soup, but for things with more ingredients also 'soup mix,' 'hot chocolate mix,' etc.)