The three yards at Aktio (Preveza) are all good. Cleopatra maybe slightly more expensive but has the best facilities. Ionion Marine is good (we are currently there) Aktio perhaps a little more rough and ready but still perfectly OK. There is a traditional Greek yard further on, we have never used it but have heard from several satisfied users.
For storage Ionion was good. Too expensive for me to get any work done. You will need a car for any of the three - you can't walk or cycle the tunnel. Cars are very cheap to rent over the winter from the airport (a 30 minute walk).
Outwith the summer there are no flights to UK. You will need to go to Athens either by bus or private minibus.