I wouldn't put bark in the shed. Woodshavings or newspaper is better (you want absorbant). I sweep my coop daily, but some people do it weekly. You're better off buying a feeder and drinker for them, just throwing feed is much more likely to attract rats. Plastic feeders and drinkers are relatively cheap. I got mine on ebay. They won't over eat pellets, but they will pig out on treats, so keep those to a minimum.
Foxes are always a problem, and can chew through chicken wire. To fox proof a run, you need to do as ABetaDad says, and you're better off using weld mesh. Alternatively, consider an electric fence. It's still best to shut the coop door at night if your run is without a roof.
As for getting new hens, google poultry breeders in your area. Hybrid hens are available year 'round, and the breeder will only sell you pullets. They cost around £10-£15 a bird, and will only be sold in groups of two or greater. There are many types to choose from, and some even lay coloured eggs.
Pure breed hens are harder to source, lay less eggs and are more expensive, but live longer and some are simply stunning.
Introductions are always horrible. The hens will fight for several weeks until the pecking order is established. It's best not to interfere too much, unless one is being kept from the food or blood is drawn.

When you put your posts in also dig a trench and bury the wire 20 cm into the ground to stop the rats digging or crawling under.

The wire in my run comes down to the ground but the rats crawl/dig under to get to the feed. Its like a McDonalds for them.

Thanks everybody

ABetaDad - questions are great - i have no idea what to expect or how to look after them so this is all really helpful.

I think we will take them but sadly if the cockerel starts making too much noise he will have to go - we cant be upsetting the neighbours. Im guessing the hens wont make noise that will annoy them?

So i get the shed/house and fence off an area attached to it for a run (some chicken wire with some posts will be ok?), i put some bark on the floor inside the shed and on the run? Put some chicken feed down on the floor and thats it ?

Ill need to clean the poo reguarly? How often do you feed them - how much? Can they overfeed themselves? They lay the eggs inside the shed and i collect them once a day?

Main problems will be keeping foxes away (I have told dh (and 3 ds's!) to go round the garden and wee! Also have dog - so shouldnt i guess have to much of a problem with foxes?

Rats - aarrgh - hate the things - not really thought about rats being a problem.

I will introduce the dog slowly and hopefully they will be ok together - if not hen they just have to stay in the run.

I guess as i will only have 1 hen i will have to get some more - now this is where i get confused - what do i get? Whats a point of lay? How do i know im not going to end up with loads of cockerels? Where is the best place to buy and how would existing hen take to 2 newbies - although they will all be newbies

I know that English Pheasant was a rare breed - how would i breed them?

Ok - thats loads of questions sorry! Any responses really appreciated

ABD: our run is huge, but it has an inside paat (ie under clear plastic roof) and an outside part.

You have to scoop up the poo on a daily basis to keep it fresh, and the bigger the run, the less smelly.
The bit in the open gets smellier than the under cover one, but the rain washes the worst of it away.

your best bet, as has been suggested, is to completely dig out your soil and replace it with new.
then keep on top of the scooping-poo regime (it only takes a couple of minutes and it's all solid, so not too yucky (I use a fire-shovel and a stick))

For the fly problem, I can thoroughly recommend red top fly catchers. I got mine from ebay, and it kept the vile things away from the hens, and the house, all summer. It does whiff a bit, but you're supposed to hang it as far from the house as you can, and at least 5 metres from the chooks.

Yeah, Stalosan F is brilliant. Can heartily recommend it

That Stalosan F looks like a super product. The run stinks and was covered in flies in summer.

racmac - hope my questions are useful. I am about 4 months ahead of you in my garden chicken keeping career and sort of fell into it without thnking. I grew up with feral free range chickens on my parents farm that really took no keeping but a garden is a much more concentrated environment.

We have a rat problem too - that is another thng to think about. Food and the eggs need to be kept very secure and the fencing round your run needs to be totally rat proof and dug in to stop the rats digging under.

ABetaDad - My girls have a covered run, and don't really enjoy wet weather so tend to stay under cover when it rains. My run is on hard slabs, and I cover that in horse bedding (absorbs the poo and smells brilliantly) which gets changed every month or so. They generally free range around the garden and eat all of my tender plants, but a covered area really helps to keep them clean. As for your run, I agree that digging it over is a good plan. Also, mixing a little garden lime or Stalosan F in will keep the ground sweet.

I killed my cockeral a couple of weeks ago after the neighbours complained about his non-stop crowing. He was waking them up at 5:00am and kept going all day, they were about 100-120ft away from the hen house. They are loud.

BCNS - thanks for that.

It has been terrible wet weather of late so will pen them out on the lawn (mainly to stop the cockerel attacking me) and then go in and give it a good dig over.

ABD you can dig over the run to freshen it up a bit if it's mostly soil ( they love it when it's a dig over day and go nuts for the worms and bugs!.. we keep ours in a run as we have foxes. In our run we have some fallen branches dotted about and lent up against the posts which they love to climb up particularly in wet weather. They also happen to love the odd straw bale thrown in. ( which when wrecked we rake out.. collecting poo as it comes out.)