It's not just "borrow from friends" that you should think about, but what is already at home.
Do you have any picnic items, rugs, coolbags, iceblocks, flask etc?
Do you have any plastic or outdoors plates, cups, cutlery etc?
Do you have torches around the place for home emergencies?
Do you have a small BBQ that could be transported?
You do need a few bits and pieces, but not as much as you would think.
Tent and sleeping materials (definitely a mat of some sort under you, and a rug under the mat, and then something warm for you either sleeping bags or duvet/blankets from home).
Something to eat off - see picnic items. Paper plates for a first trip are fine to see if you enjoy it. I use Ikea's kids plastic plates and cups, as they are cheap and non-breakable, and the plates have a lip to hold wet food when they might be at an angle on laps.
Lighting - a headtorch each is really useful, but they can be very cheap. A headtorch turned around to shine through a full water bottle magnifies the light to make a lantern for the tent. Having 1 handtorch is also useful - again there are very cheap models out there.
Cooking etc - think about food that is easy to prepare. You will want some heating option to heat water for tea and a small amount of cooking. I have a 1 ring gas stove from Halfords (it's about £18 nowadays) that works fine to boil water and do some cooking, and I have a mini BBQ from the middle aisle in Lidl/Aldi (about £10) that I use to cook dinners on - grilling meat and skewers, cooking in foil parcels, baking potatoes in the coals, roasting marshmallows for dessert etc. (And throw the kettle on top once finished to get hot water for tea/washing up afterwards). You can put a pot/tin with the LID OFF (eg baked beans) on the BBQ grill as well if you need some extra cooking space. If you have leftover hot water at any stage, put it in a flask so you can use it later.
But also - salads or sandwiches, food that only needs hot water (couscous, microwave pouches of pasta or rice, smash-type mashed potatoes etc), and 1 pot meals are useful to consider. Buy a rotisserie chicken and crusty bread from the shop en route back to the tent one afternoon for that evening's meal. Have things like brioches/pastries and fruit for breakfast rather than hot cereal.
But have fun things too - like one morning, do pancakes for breakfast - measure out and put the dry ingredients into a bottle at home, add the milk on site and shake throughly, pour onto pan. Or french toast is very easy on camp as well - just whisk an egg on a plate, (maybe add a dash of vanilla if feeling decadent), dip the bread and fry up. Make up the sauce for 1 dinner at home to just reheat - maybe chill con carne that you serve over tortilla chips rather than rice, or using microwave rice pouches (add some boiling water and let that sit for 5 minutes instead of microwaving). That can be useful if frozen to keep coolbox cool initially as well.
You will need a container to carry water - but a 5l bottle from the supermarket (with a handle!! to carry it) works fine and you can refill that on site as needed. Perhaps 2 bottles if you have a few people to cater for, to reduce the number of trips to the tap.
Bring utensils from home, a bowl to mix things, a couple of spoons, a couple of decent sharp knives 1 small/1 larger (that you protect the blades with a sheath made from cardboard or similar), spatula etc. And a pot and a pan (can boil water in the pot if need be). Roll of tin foil.
Table and chairs - you can just sit on a rug, but really a couple of chairs make a big difference. If you have any folding chairs for the garden already, and space to bring them, they would be fine.
Lots of camping shops have £££ items - but you can also get basics cheaply in lots of places. Decathlon is good, Lidl/Aldi both have decent camping and outdoor items in their middle aisles at times, Halfords, Regatta etc. And look for second hand as well.