Dead easy
Get on A-7 south from the airport - At fork in motorway where A-7 heads for Murcia - Keep on AP-7 heading for Catagena until junction 786 ( Los Narejos / Los Alcazares )
Junction numbers denote km's - so you can always tell how far you have left to go
As you drive up this slip road you will see Roda on your RHS
You will cross over the AP-7 and come to a roundabout - take the first junction to Los Narejos / Los Alcazares ( Av de Catagena )
At first roundabout - take right turn to RODA
You will cross back over AP-7 - and RODA is on RHS
Will take around 45 mins - all motorway
You will need some EUROs for the toll portion around Torrevieja