I'm probably repeating lots of other posters, but here's my few bits.
Either a 1 ring gas cooker (there are seriously cheap options) or a couple of disposable BBQs are definitely worth having even if you are unsure about investing long term. We have refilled the BBQs with fresh charcoal when used up and cold again in the past (bring a pliers and pair of work gloves as the mesh can be sharp!). If using a BBQ, plan your use so put a kettle on top while it's getting going for hot water (and any other pots you want heating) before doing the actual BBQing when coals stop flaming and get to ash-covered embers glowing. Stick the kettle back on after for washup water or to put in a flask for later tea/coffee to make the most use of the heat.
Also, check locally for takeaways etc - may be very handy for dinners. Or good delis that might do a rotisserie chicken and crusty bread and salads that you can use as a dinner.
If you have 1 gas ring, you can easily have a kettle for tea/coffee/hot choc on water (we use Lidl hot choc powder, made on boiling water and add milk to cool down for Cub camp and it's LOVED). Also for pot noodle or similar "emergency meal in a tub" options (there are some very good ones nowadays), or morning porridge in a tub (Flahavans do nice ones).
Breakfasts like long life croissants or brioche are lovely, or cereal. But also if you have 1 ring, once you've made the all-important morning cuppa, you could put on a frying pan and make "camp pancakes" - weigh out the flour/sugar/baking powder etc ahead of time and put into a ziploc bag or clean empty milk carton with a lid, then at camp, add your milk (and egg if using), mix thoroughly (ziploc can be squished well, milk carton shaken vigorously - obviously reseal first after adding liquid!), and pour onto the pan. For ziploc, could snip a hole in bottom corner to carefully pour (that has more control than opening the top), and close again with a clippit/peg.
Bacon sarnies off a camping pan are also a great breakfast.
And 1 ring is plenty to do so many different dinners - risotto types, pasta with sauce thrown in to heat after draining water off, boil potatoes but put fish into ziploc to cook in same pot at the same time (sous vide style).
Microwave rice and pasta pouches cook very quickly and easily in a minimum of water (empty pouch into a pot with a couple of tablespoons of water, cover with lid or tinfoil, cook for about 3-5 minutes) - so can be done after you cook the bits for adding (chicken, bacon, veggies etc, and a sauce) - put those into a bowl, use the same pot to cook/heat the rice/pasta, then add back in the meat/sauce etc to stir through and serve.
And if you have a BBQ - don't just think sausages/burgers/steak etc, think chunks of veggies on skewers, tin foil packets of meat/diced potatoes/veg/seasoning together, or of mushrooms with butter, etc. Bananas can be cooked in their skins. Potatoes can be baked (in foil), and apples too - I core the apples and put a mix of brown sugar, raisins and cinnamon in the middle. Marshmallows on skewers, then eaten between 2 biscuits (especially if half covered choc biscuits with choc facing marshmallow and "clean" side facing fingers) are also great.
Popcorn can be made in a pot on any heat source, but if you have a BBQ or campfire, use 2 metal sieves facing each other to make a round ball, put the contents of a bag of microwave popcorn in the middle of the ball, and heat over the fire/coals. Just make sure the sieves are tied together using something like some metal wire, or pieces cut from an old metal coat hanger, (so popping doesn't force them open too early) and that you can undo one side of that tie when it's ready to get at the results.
Oh, and always extra socks. Keep a clean pair that never go outside the tent for putting on at bedtime (important to not get cold at night generally).
Warm hat for sleeping in - your head is the bit sticking out of the sleeping bag and also loses most heat of your body.
Ikea blue bags are very handy for each person to have their own things in, root through easier, and to toss things back into when tidying tent.
If you have a water barrel (or a 5l bottle of water from supermarket), put a head torch around it and turn the torch facing INTO the water, makes a brighter lantern than just the torch on its own.
I have a rug on the inside of my tent door to avoid mud elsewhere, and take off shoes just there too. But before I got the rug, I used to carry groceries to camp in a cardboard box, and then flatten it and use the cardboard as my rug - throwing it into the recycling as I left.