Hello Noel and welcome to the forum
Your house looks lovely
however I'm not too good at judging dimensions. What have you used for the roof? Internally what I have read is that you will need 18ins perching space for each hen. If they can squeeze up cosily in the winter they keep each other warm.
From your picture I can't see any ventilation. Is there a ventilation grill at the back?
Will you be letting your hens free range or have an enclosed area? You will need a minimum of two square metres of ranging space for each hen, preferably three.
I use dust extracted wood shavings both on the floor of the coop and in the nest boxes.
Hens love to scratch around and it is important that they have an area where they can have a dust bath. If you are keeping the coop where it is you may want to consider a large tyre filled with a mix of sand and earth where they can dust bath.
What anti-predator measures are you taking?
Good luck with your new hens and keep us posted