Hi, I am new

Depends really.
Are you going to have them in a permanent place, or do you want to move the coop/run around?
Are they going to be free range for a while in the day?
How big do you want the coop and run to be?

When we were building the coop (wooden), we were told that it needs to be big enough to hold 2 more hens than you are actually going to have so they have plenty of space to roost.
Ours is big enough for 16 so the maximum we could have is 14 - we had 12 at most at one point, now we have 11.

Oh and despite there being 3 perches to roost on, the girls have to snuggle together on the highest perch!!

Also depends on how much you want to spend.

Some of these plastic Eglu type things are quite expensive. Wood would be cheaper, particularly if you can find some reclaimed wood and recycle it.
Of course you have to treat wood as well.

I think long term,  plastic would be better.

They are more expensive but go for a good quality one, even if it means saving up for a few more months.

Have a look on Gumtree as well as they seem to have some great bargains on there.

Things to think about as well are fox / rodent proofing, and who will look after them if you go on holiday.

My only other advice is read, read and read a bit more, ask lots of questions (no matter how silly they may be) and try and find a poultry friendly vet before you get the chickens.
The last thing you need if you have a sick chick is spending hours ringing round vets that dont do chickens.

You wont regret it 

Hello
welcome to the lovely world of owning chickens, have a look at 'solway recycling' they have some resonably priced coops, just make sure you have a large enough run if thats where they will spend alot of the time, most coops with attatched runs arn't big enough to keep them in they usually quote on how many hens for the coop not for the run. Order your flubenvet now, its the prefered wormer its easy to use and there is no egg withdrawal. let us know how you get on and also we will need pictures of the new hens!

I was a beginner 2 years ago and I did an Omlet course on a Saturday morning (there will be one near you).  It was £20 and so fun and intersting.  They show you the Omlet stuff but its not about selling to you - its all about chickens and I cameaway feeling so excited!

You won't regret it - hens are so endearing.
They each have mad little characters.