Since this control has moved this year, according to the AUK summary, it's going to be a bit of an unknown.
Well spotted !
Tre'r Ddoll would make for a rather long second leg, and the provisional route sheet mailed out last earlier this month still stays Nant Yr Arian
Where you saw the Moultons would have been the Red Kite (?) which AFAIK used to be a control and was also very slow in times gone by.
The garage in Ponterwyd is a good alternate.
Yes, it was the Red Kite (from StreetView). The garage at Ponterwyd doesn't have much in the way of "food", more in the way of "snacks": I stopped there last year with the hope of getting a sandwich and only managed a milkshake, a packet of crisps and a restock of Jelly Babies.
If it's Nant yr Arian again this year then, unless I am somehow a couple of hours quicker than last year, I will be buying a car-park ticket and heading down the hill to Tre'r Ddol, which has a pub, a garage and the aforementioned café. Oh, and of course since it's mostly downhill or flat from Nant yr Arian then it doesn't feel much further (but it wasn't raining last year).
One other tip: if you find yourself with not much time in hand on Sunday, find someone who looks like they are still going strong and shamelessly suck their wheel all the way to Chepstow ... thanks, PpPete!