Dang... I just got my 1/500,000 map and it's the wrong Talybont.
Still the closest airfield, but unfortunately you need to go inland past the Dovey estuary, then back out to the coast.
Google maps reckons it's 36 miles - a 2 hour round trip.
Thanks for the suggestions re. Rosemarket - unfortunately not really the region I was looking for though, which according to the Welsh assembly is 'Central wales' which isn't a place I knew existed.