[Melosine]

May I suggest you research Aguilas, Murcia.
Very attractive Spanish coastal town with NOT an English shop anywhere a d only Spanish bars.
Most unusual these days.
Does however have a sprinkling of expats of all nationalities within Aguilas, Lorca area who have weekly meets on Plaza de Espania for those who feel inclined

 

[Melosine]

Times are changing, dancing spider.
Chinese restaurants have always been very popular with the Spanish and Valentines day husband and I were the only 2 Brits in a busy Indian restaurant , and not for the first time.
Same with Fosters Hollywood, Mexican and all the fast food emporium
These all in Lorca area which is 99% + Spanish city.

 

[Melosine]

Campello is pretty dead in the winter and in the summer the population is 3x to 5x more... It does have a nice surfing spot tho.

Gandia is a nice town. Train to Valencia is easy...

Another option would be the villages of the Valldigna or around Sanguto - Camp de Morvedre .

You will hear hardly any english spoken in any of the above villages..

That is the best, or perhaps worst, (because sometimes at certain times of day parking is difficult ) as Aguilas is busy all year.
To be honest unless one is a child or extremely gifted fluency in adulthood is difficult and hearing another speak you language is comforting.
Personally would love to hear of other resorts that are free of British establishments.
There must be some