Santander/Gibraltar

Qashqai66

We enjoy France so much that we have never gone to Spain.  France is easy as I have not lost the habit of speaking French but cannot remember much Spanish from schooldays 60 years ago. I now plan on  refresher Spanish course so that we can book the ferry Plymouth and cross to Santander.  Our plan is to drive in the motorhome down to Gibraltar and then cross to Morocco.

Can anyone recommend the best route across Spain please?  We prefer not to use mountain passes but do not was the trip to pass in a blur of autoroute tarmac.