You can drive right up to it along a tarmac road. There are two gates, one at the edge of the forest and one a little further on. I have seen the outer one locked before, but it was wide open when I was there on Sunday. There is a cottage along the track that seems to have recently been bought. The drive is being badly landscaped at the moment, but I don't think you'd be waking anyone up as the cottage is still a (presumably unliveable in) kip. You will have to take two wheels off the road at the moment though as whoever is building the walls has left a couple of huge boulders in the road. Alternatively you could park by the cottage and walk the 300m or so to the tomb. It's a wonderful place. As the tomb is built on a small rise and the trees are well back from it you should get some good sky behind it.