No special access issues
Two approach paths exist, depending on which boulders you are heading for.
For Saturn boulders, park in the Tryfan carpark (actually a layby) on the bend in the road and go though the obvious gate. Saturn and the surrounding boulders should be within view. For Bombshell, follow the path up but trend rightwards, going over a style heading to the bottom of Milestone Buttress proper. The problems are in the cluster of boulders immediately in front of you.
For The Pit, park further down the valley towards Idwal cottage in the large walled car park. As you drive in, there is a gate to the left hand side of the car park. Go through this gate and take a vaguely straight line onto the plateau directly in front of you; a path of sorts does exist, although can be tricky to find. From the high point on this little plateau, the Pit will be to your right.