The Central Coast is not an unsafe place to live, it's safer than most parts of Sydney (especially western Sydney). My advise would be to stay away from The Entrance(even thought it really pretty), San Remo and Watanobi and go for places like Forresters Beach, Wamberal, Copacabana, MacMasters Beach, Pearl Beach and Patonga. Terrigal & Avoca are nice but very crowed in summer.
Umina and Woy Woy, Bookerbay areas are probably cheaper than the above with Killcare, Avoca ect being a more expensive... i lresided at most of these over a 20year period and i love holiday time in summer on the coast best times THEN !!!!