Hi Wellies101 welcome to the henhouse! I wouldn't suggest starting off with day old chicks as you have to have them under constant heat for 4 maybe 5 weeks and its the wrong time of year, especially for a beginner.
You are better off starting with some POL's like you say 16 weeks+, get used to the chickens then decide if you want to expand into chick rearing!
Even ex batts lovely as they are, can have health and stress problems, so would be better for later on when you have more experience.
Galvanised drinkers and feeders will last a lot longer than plastic ones, but are a lot more expensive, unless you can get them at an auction maybe? But if you ever buy anything 2nd hand, then make sure you disinfect it well as they can harbour nasties that could make your new girls sick. We buy our feeders and drinkers etc from
www.solwayfeeders.comThey are very reasonably priced and as they are farmers, if you have a question about a product, they are very knowledgeable too.
We tend to use layers pellets for ours as they are less messy than layers mash (or meal) some shops call it. Give the pellets ad lib then late in the afternoon let them have a few treats. maybe some mixed corn or kitchen scraps. they love pasta and rice, and green stuffs and fruit, but just remember, everything in moderation, and nothing with salt, sugar fat or milk in, unless its a probiotic yoghurt if they are ill and need a little help to get better.
Chickweed and dandelions and cabbage leaves are very good for them.
I'm sure others will be along to offer more ideas soon! Good luck!!!
As to breeds, I'd say start with hybids which are cheaper to buy, if you do have any problems with them, then it hasn't cost you the earth.
That coop sounds a bit small. Are the dimensions you mention the whole thing run AND coop? DEFRA minimum requirements for the coop are 1 bird per sq foot, but even that isn't really enough, with 1 bird per sq metre of run, which again isn't really enough. How big is the coop?