Hi Crookes
The road to Cadianda is rough but it is accessable by car provided it's fairly high off the ground.I have seen a taxi rank somewhere on Calis promenade listing Cadianda among its destinations.
Failing that you should consider hiring a jeep for a day in which case getting there will be no problem. When you get there it is a fair walk around the site as it's quite big. I think the entrance fee this year is about 7 Ytl.