OBNB doesn't sell books, but you may be able to find a copy at one of these websites:
Blaenau Gwent : gwybodaeth i bobl fyddar a thrwm eu clyw = Blaenau Gwent : information for people who are deaf or hard of hearing. Published by RNID Cymru in 2010. Publication and catalogue information, links to buy online and reader comments.