Hi Naomi and welcome! Good for you for doing this!
Learning to cook and prepare plant based food is important to ensure you eat a variety and don't get bored. I would recommend visiting your local library and reading vegetarian cookbooks. Often they have sections in the front with staples to keep on hand and techniques to use and so on. I read a TON of cookbooks in the beginning, and would visit blogs online too in order to learn the secrets of plant based cooking.
Also, keep snacks on hand for work and family events and traveling. That way if you get hungry or tempted by foods you are trying to avoid, you will have something on hand. The nomeatathlete website Ledboots shared with you on another thread has a great recipe for energy bars. I make a bunch of them and freeze them individually. Once I take one out of the freezer (whether for long distance hikes, working, traveling etc) it keeps for a whole day and still stays nice and firm. Here is the link to how to make them:
Commercial bars like Cliff, larabars, Luna etc are all vegetarian too. And fresh fruit is an awesome snack to have around as it keeps a long time without refrigeration and is satisfying and filling. Homemade granola, whole nuts and seeds, tortillas with peanut butter or hummus are great snacks too.
And don't be too strict! By that I mean don't cut out all possible fat, gluten, soy, etc. and live on brown rice, veggies, black beans, and chia seeds lol. Learn to make veggie pancakes, and homemade bread, and have thai tofu stir fries! If you keep an open mind and eat a good variety of plant food, I promise you will never be bored! Heck, you can even make "fudge" or frosting just by blending avocado, maple syrup, and cocoa powder! It's a treat but still has very healthy ingredients in it.