Have the Auchan Gasolinera Alcampo at Irun fixed into both sat navs and try to fill either way as it's always cheaper.
The Mac Donalds is total crap but we use their loos. Walking round the supermarket gives us an exercise break.
That's the one you recommended to me Ray when I had to hotfoot it up to Cherbourg when the Santander boat was cancelled last November.
I was able to stay overnight there n felt very safe.