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I've only ever taken a stove once while biking so I tend to visit shops - they can be an adventure in themselves. Having done some Scotland riding with a stove though (and fewer shops) it's quite lovely to have a hot meal by your tent without waiting for shops to open or without having to ride 50k before you find a coffee in the morning. So, if touring, I'd now take my small stove and some coffee as well as porridge sachets or premixed ziplocks of it and maybe some savoury boil-in-the-bag meals.
I've seen people do "proper" cooking but I ain't got time for that.
It's a lot flatter if you go further south.
I've ridden some of the same roads you're on but during Transiberica where I'm picking roads for speed, not niceness. Can't really comment on any of that other than Spain is much nicer to ride in than UK so you don't need to be as wary about finding yourself on bigger roads - they often have big shoulders and the drivers aren't pricks like here.