Will post pics of our garden and chicken set up when I'm back at home.
Check on the council website that there aren't any restrictions, most are fine as long as you are keeping them as pets, giving eggs to neighbours & a reasonable number of them etc not to be commercial, but there will be regs somewhere on domestic fowl keeping.
Don't get a cockerel - noisy beggars and will not endear you one bit to your locality.
Hens are pretty quiet but have a range of noises to let you know when they're happy or want a treat (mealworms are a fave), if they have seen a cat or laid an egg. Their noises are so endearing. Out of courtesy I'd tell the neighbours in advance and reassure them it'll be quiet. A few eggs help once they start laying.
Eggs, usually one every couple of days, it generally takes 24-25 hours to brew one.
They are surprisingly hardy critters and plenty weather resistant for out York's/Lancs climate. We've never had parasite or red mite problems but its worth an annual treatment in their bedding area to be sure.
They like.a.slightly discrete area to lay in, some coops have an extension like box on the side, ours has a lid over the nesting box to hide it.from their perching bars. 3 sleep on the bars, one sleeps in the nest box, purely their choice.
Laying problems/being eggbound can be a health problem, if you do have such issues, they can be implanted with a false egg to solve it.
Our dogs and the local cat population leave them in peace - they have pointy bits to protect themselves with.
Dunno if you're rescuing (please do - Google British Hen Welfare Trust as a 1st stop) or buying , if rescuing they may come to you a bit scratty and missing some feathers, as you see them liven up and their personalities develop & feather up its a great warm fuzzy feeling.
They can scrap a bit but ours have generally been fine with each other and we've had no bloodshed or bullying, but it can happen so consider if you could have a segregated area too for acclimatisation - very very unlikely to be a problem with a couple though.
Vet bills are negligible but look around for one who takes chickens seriously, our dog vet has an its only a chicken attitude and is too quick to suggest euthanasia rather than treatment if they do get poorly.
I would definitely set them up in a run in the garden so they have their own space to scrat and leave barren. They will eventually reduce however much room they get to a mudbath. Our garden is approx 40x20 feet and I let them forage it freely last year to start afresh this, 4 of them did it in a couple of months.
Ours have an enclosed run for when we are out and a fenced piece of the garden for when there's someone in.
Set your enclosed run on slabs or a concrete base and extend this for 6 inches or so beyond the edge of the enclosure. Foxes can dig into earth but are stupid, they'll dig right at the enclosure wall & with the solid 6 inch skirt there will fail, but won't think to move back and try to dig under the skirt edge. The solid floor inside the enclosure both helps with protection and is far easier to clean and keep the birds tidy.
After the initial financial outlay - coop and run mainly - very cheap animals to run. Sawdust for their egg box, wood chippings for the run floor, food is cheap & lasts ages.again, if rescue start them on a layers powder rather than pellets and over a couple of weeks incrementally introduce and replace their diet with all pellets.
They drink water, a bit of apple.cider vinager helps their condition - on cold days they have warm water and we'll give them a breakfast & supper of human porridge oats with a few mealworm in.
They'll eat mostly whatever you give them but read up on what is and isn't good for them then experiment with their palate. Ours have a sweet tooth and love corn on the cob - on hot days we'd make them sweetcorn lollies, loose corn frozen in water (pampered? our girls? hahah)
They need a constant small supply grit/crushed seashells as a diet supplement to be able to digest their food. Literally small amount, we have an10kg bag and it will last us many years.
If you are handy with a saw & hammer then build your own, its only a wood and chicken wire box/lean to.
Proper fresh eggs taste so much better.