From junction 20 of the M5 take Clevedon/Yatton exit (it's the only exit on this Jct), as you do so get in the left hand lane and bare left at the next roundabout following signs to Yatton.
In about 3/4 of a mile you'll come to another roundabout (there's a Tescos store/petrol station here) again bare left following signs to Yatton.
Stay on this winding road, which takes you through the village of Kenn, for about 2.5 miles.
After a sharp bend you'll go past 'The Bridge Inn' (on your right). You'll then come to another roundabout, go straight over it and you'll see Yatton RFC after about 100m on the left.