You're missing nothing at Pembrey.
I wrote about my visit there on the other forum last month. Despite two pre-visit telephone calls and a faxed GAR, he neglected to tell me that he didn't have fuel until after I'd landed. He left me in the position of having to do some creative thinking, to get fuel and comply with my GAR, at 1730 on a Saturday afternoon. As you've noted, Wales is closed.
Thank goodness the flying club at Haverfordwest were very understanding, as were the police.
I will never go there again. Never.