Hi Sammy,
I got it from Dobbies garden center. They are more a Noth of England shop I think and ours is one of the furthest south of their stores, not sure you will find them where you are.
Bark is easier. I get that online/mail order from 'Orchid Accessories'. You can ring them on the number on the website and they are very helpful. I have been very impressed by the quality of the bark and CHC that I bought from them, and very pleased by the knowledge of the people I spoke to.
Orchid Accessories - www.orchidaccessories.co.uk