hello Stuart,
Turn right as you come out of the ferry port,Follow the road untill the big road junction with the Traffic lights(follow the Sadari signs)Just keep going alone this road,its a duel carrageway along the front,Do NOT take the Dassia turning,keep going until you come to a tuning on your right for Sadari(the other way takes you to Paliokastritsa),you should start climbing in a few minutes,just keep going up until you go through the Troupetta pass right at the summit.the road starts to drop down the other side.On the second or third right hand bend is the turning on the left for Arillas,take this road,,go through the first village and straight into the second the road then turns to the right,just follow this road until you come to a biggish village with quiet a few shops,Here is a very sharp(swichback ) turn to the left take this,keep on this road for about 15 minutes,you will see a bank of road signs the road goes straight on or turns left here.Take the left turn about 2 minutes later you see a t junction left here then look out for the sigh for Arillas you are about 1 1/2 miles away,you turn right and start to drop down(strainght on takes you to Afionis).At the Tri Adlephi the road splits ,its just a big circle,but going right is the best.Road signs are in both Greek and English,will fish out the map this weekend and put some village names in.