Danger Area info is in the AIP
here. (Direct link).
To find it in context on their site, start
here.
From the first link (in part):
EG D117 Pendine
Hours: Mon-Fri 0800-1800 Winter (Summer 1hr earlier); and as notified.
No firings on Public Holidays.
‡ EG D118 Pembrey
Hours: Mon-Thu 0900-1700, Fri 0900-1400 Winter (Summer 1hr earlier);
and as notified.
For Pembrey, when open:
‡ Note: Aircraft operating in these areas are unable to comply with Rules 8, 9, 10 and 11 (Rules of the Air Regulations 2007). Pilots in the vicinity of these areas are strongly advised to make use of a Radar Service.
I think there's info on the chart legends as well, isn't there? (I don't have one to hand)