Nicked this from another site. Good old copy and paste:
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Via the M4 - From Swansea, Exit the M4 at junction 37 and follow the A48 towards Bridgend. Continue along the A48 and after the 2nd roundabout there wqill be a right turning signposted 'Merthyr Mawr'. Take this road and continue to the end of the road. At the T-junction turn right and continue along the B4265 through St. Brides Major, after leaving St.Brides Major take a right, signposted 'Broughton, Monknash, Macross', and continue along this road until you reach a triangular green. Turn right at this green and drive past the pub continuing along the road. Towards the end of the road is a farm with a car park (nominal fee), PARK HERE. The road continues here for another 100yrds or so. Walk down this road to the end, there will be a gate and footpath you will need to follow on your left hand side. Continue down this track for ¼ hr until you reach the beach. The main beach is then to the right.