Yeah, if trying to lose weight and learn to be healthier, ready made meals are probably not the best way to go.
Breakfast:
oatmeal is very easy. You can buy it in bulk or a canister and it is VERY cheap. To make, measure out some oats into a bowl. One serving is 1/2 cup dry. I usually eat two servings (1 cup dry and it comes out to 2 cups cooked). Add a little cinnamon spice if you wish. Heat some water in a pan on the stove. If you have one serving of oats (1/2 cup dry) you would need 1 cup of water. If you have two servings, you would need 2 cups of water. Heat the water to almost boiling, then pour it over the oats in the bowl. Let it soak about five minutes and you have cooked oatmeal. I like to add frozen or fresh berries to mine, or a banana, or nuts or seeds, or a combo of the above. It doesn't get much easier than this. I do not add sugar to mine. The berries and/or banana make it somewhat sweet. If you want more of a salty effect, add some chopped walnuts or almonds, or a tablespoon of peanut butter.
Beans on toast. Bread can be tricky as so many are not vegan due to honey and added D3 or other strange ingredients like L cysteine. Sometimes you can find vegan bread in the freezer section of your grocery. The reason they are there is due to not adding preservatives to be shelf stable. These are often vegan friendly. Otherwise, you will need to do some research to find out what brands of bread are vegan in your area (I am not familiar with the U.K.). Once you figure that out, and where to find it, life gets easier lol. I tend to make my own bread which is cheaper and easiser yet, but I understand when you are new to cooking that would be overwhelming. At any rate, I like to add black beans and salsa over toast, or can of fat free refried beans (full fat ones usually contain lard), or white beans and blackstrap molasses over toast.
Another simple breakfast. I cube a serving of tempeh or tofu (if a package says it has three servings, I divide it into thirds etc). I add it to a nonstick skillet. I chop some collard greens, or kale, or chard (usually about 4 large leafs) and add it to the skillet. I chop some fresh pineapple and add that too. then add a little water, just a splash, less than 1/4 cup. Heat on medium heat until the leafy greens are soft and tempeh is heated, about three to five minutes. I add garlic powder or ginger powder to this, and a squirt of soy sauce. Simple healthy breakfast, high protein, and the pineapple adds a nice flavor to the leafy greens and tempeh.
Lunch: soup is the easiest dish to learn to make. you really can't go wrong. add a can of beans to a pot. Chop some onion and add that. Here are some vegetables I like to add: chopped bell pepper, zucchini, green beans, minced garlic (you can also find this in a jar already minced for you), broccoli, collard greens, tomatoes, tomato paste (can), celery, carrots...The soup can be as simple as a can of white beans and chopped carrots and curry powder. I usually just add water, enough to cover all the beans and veggies plus a few inches above. Vegetable broth or stock adds flavor also. I add spices like basil, oregano, garlic powder, cumin, chili powder etc. I have a lot of bottled spices. They help make a very flavorful soup without the need to add loads of salt. Let your soup simmer for twenty minutes or so to get everything soft. If you want a creamy soup, you can add the batch to a blender and blend. If you have a small blender, add a little at a time, blend, pour into a bowl, then add more to the blender and so on.
Sandwiches (some ideas for a vegan sandwich):
sliced tempeh and sauerkraut
hummus and black olives
peanut butter and banana
chickpea salad sandwich (find some vegan mayo...Just Mayo, Vegannaise, Nayonaise, Spectrum eggless are all vegan mayonnaise brands I am familiar with). In a bowl, add a can of chickpeas and then mash them down with a fork or potato masher. Add some chopped celery and onion, then add a few tablespoons of vegan mayo and mix all well. Add some black pepper sprinkled on. Then add to a few sandwiches (I can get three or four sandwiches from one can of chickpeas). This sandwich is very much like egg salad vegan style.
To go along with your sandwiches, or for a snack:
any fresh fruit...apples, pears, grapes, bananas, peaches, plums, apricots are all portable fruits you can bring to work or travel with easily
pumpkin seeds or sunflower seeds with shell on, usually roasted and you can find these prepackaged if roasted. Makes a nice snack. I add a handful to a baggy, then add chopped dates or raisins in with them for a sweet salty mix.
garden salads are always great. You can add anything to them, even beans or raw seeds for a boast of nutrition. Dressing can be as simple as balsamic vinegar or a squirt of lemon juice. Or, for a heartier dressing, add a few tablespoons of peanut butter, up to 1/4 cup, to a small pan on the stove. Add a pinch of cidar or rice vinegar or just plain vinegar (about a tablespoon). Add a tiny bit of soy sauce, and a tablespoon or two of water. Heat to soften the peanut butter into a more liquidy but still thick concoction. Add this to the salad. I also like to add turmeric powder to my peanut sauce but it's not necessary.
Dinner:
whole grains like brown rice, bulgur wheat, millet, quinoa, couscous, wild rice etc are all great as a base for a meal. Add some beans, spaghetti sauce or vegan gravy, and some sauteed veggies to the mix. Sauteeing simply means adding your items to a pan or skillet and adding a little oil or water (only a tablespoon or two) and heating the items.
baked potatoes are very easy, but take time to heat in the oven. Some people microwave them but I have not done this. I like to add steamed broccoli to mine, and a sauce. My sauce is simple...nutritional yeast flakes, plant milk, a pinch of cornstarch or other starch, some spices like marjoram or garlic powder or even dijon mustard. I heat this and stir to make a thick "cheese" like sauce. Then pour it over my baked potato. There are vegan commercial cheeses on the market you could add to your baked potato, but they tend to be less healthy and more calorific.
If you can find a steamer basket somewhere, this makes cooking so much faster and easier. I can skin and chop a potato or sweet potato and add it to my steamer and have a soft potato/sweet potato in less than fifteen minutes. Vegetables like broccoli, asparagus, carrots, cauliflower are also very easy to steam and take mere minutes to soften. When you learn to cook more, carrots, sweet potato, and cauliflower are all great bases for making a vegan sauce. I can make alfredo sauce by blending steamed cauliflower, almond milk, and spices, and a little blanched almonds or olive oil too. It makes a simple creamy sauce that goes well with pasta or over a baked potato. no fancy ingredients there. Blending cooked carrots or sweet potato with nutritional yeast and/or nut/peanut butter and plant milk (especially coconut milk) also yields a rich creamy sauce.
It does take time to build a vegan kitchen as far as ingredients. Once you have some basics, cooking becomes much easier.