Hi,
Not that I am aware off. I think the best advice is to stick with the main roads, and follow the instructions for accessing the site from the sites listing, the site books etc. If you are using a SatNav be aware that some may send you down less than suitable roads! Whatever navigation aid you are using, SatNav or a standard map it is always worth checking out the details and remaining on the A roads for as long as you can. As you get near the sites, you will find the roads will become narrow and worrying. Just take is slow and be careful. Enjoy.