Hi, and welcome,
firstly and most importantly don’t panic! Pre diabetes can be managed and even reversed, and it sounds as if you have room to change your diet to help reduce your sugar levels. Did your doctor give you your actual test results? The important one is something called HbA1c. Knowing the level of that would tell you how far above normal you are, and help you decide what changes would be useful.
you are absolutely right that ready meals are full of carbs and added sugar so I suggest the first step is to cut them out if possible. Simple home cooked meals with fewer carbs would be better if you can. It’s possible to batch cook on a day you have time, freeze portions, and then you have delicious home cooked “ready” meals in the freezer. What kind of meals do you like to eat, and cook? Maybe we can help with some suggestions?
ask lots of questions here, there is always someone to help.