Hi Kev,
Abercrave is on the A4067 NE of Ystradgynlais.
Its approximately 14 miles West of Merthyr Tydfil.
Your easiest route from Cardiff would be to Merthyr then West on A465 past Hirwaun and down the Glyneath bank and take the first turn off to the A4109 past Severn Sisters and you eventually emerge on to the A4221/A4067 junction right in front of the village of Abercrave.
Turn right at the junction and travel about 800 yds then turn left into village, at the top of the rise you will see the pub on the right.
See you there at about 7.30 pm