You will probably only need the sat nav to visit places. Finding Las Terrazas is pretty easy from either Alicante or San Javier airports.
Basically take the AP7 northbound from San Javier, southbound from Alicante.
Exit junction 782 onto the C-3319 to Balsicas and Murcia and quickly take the RM-19 to Balsicas and Murcia.
Exit the RM-19 to Roldan, Balsicas and Gea Y Truyols and take the RM-F12 to Roldan.
Before you reach Roldan, you will see a sign for Las Terrazas.