Good for you!
A bit more info would help.
A "bike tour" can mean a lot of different things to different people.
An idea of distances you expect to travel (total & daily) will help. As will your style. Some people race, others smell the roses - and everything in between.
Ate you going solo? What kind of touring experience do you have? If none there's a strong argument to be made that that's the best kind!
Pretty much none of the following applies if you want to race.....
How far? The Atlantic Coast route goes through the middle of Spain - a long way from the Atlantic
If you search this forum there's a thread with a loooong post by me about the Camino Frances. There are many different Camino routes in Spain - not all of them in the north.
My personal thought on that is to either do it as a pilgrimage or do it as a bike tour - they are very different experiences.
One suggestion is to do the Camino Frances (the most popular) in reverse! I've recently done some of that and on the narrower, rougher roads it made a big difference to be approaching walkers from the front.
This is the real thing that struck me.
You appear to have the one thing that most aspiring touring cyclists need - time!
If you're concentrating on Europe there's no need to slavishly pick existing routes but to go to the places you want to visit.
So where are they?
That's something that will vary from person to person and possibly is influenced a great deal by experience. Some people thrive on randomness while others suffer from a lack of destination.
I make up my route every day and change it frequently (a thing that would drive a lot of people crazy) but try to have intermediate destinations, say a week or 10 days down the road.
But.... I have a GPS that I understand and access to a couple of apps that I trust based on my experience. Without those I don't think I'd do what I do quite as freely.
Why EV1? What's there that you want to see or visit? France has got wonderful roads for riding on - as well as other bike routes - you can go anywhere you want.
(I've done a lot of the French part of EV1 and loved it - but put me beside water and I'm pretty much in heaven. Other people have found it boring.)
It's all well and good for
@Sallar55 to say this and I tend to agree but they appear to have toured in most places around the world. Your experience may be different.
A bike that cannot do roughstuff for example it isn't geared for steep climbs requires more detailed planning.
And here's the thing about the Internet - I can wax lyrical a out a place for touring or a method for planning or ..... Anything but that's no guarantee that you'll like it.
It doesn't matter what others do. It only matters what you want to do and are comfortable with and what works..... For you.
If I was in your shoes I'd head over to CrazyGuyOnABike and start checking out the journals. There's bazillions. I find it helps to find people who speak to me that I can say to myself "if they can do it I can".
It's a good way of figuring out where you might want to visit.
Lots of stuff on YouTube as well but I prefer the written word.
A search on Amazon for bike touring will throw up lots of suggestions too.
In other words I wouldn't be planning, I'd be getting myself inspired.
I'd also be asking myself just where I'd like to go. Then look to see how I can do it on a bike. What are you interested in? How can that be blended in to a bike tour?
And in the meantime I'd be out on my bike as much as possible and testing out my skills - cooking, camping, repairs and my gear, my GPS, my route planners so that I have the confidence to be out on my bike for that time.
Much better to practice pitching my tent in a storm in the garden (or a friendly farmer's field) than on a mountainside in Spain for the first time.
I was very lucky with my first ever bike tour. It was booked at the last minute and I knew nothing of cycling fora. Ditto my second and third. It was only when I came online that I realised just how complicated it all is!
It's only as complicated as you let it be. At the end of the day it's riding a bike from place to place. I find it helps a lot to be going to places that I want to go.
One thing to consider if solo is that three months can be hard for some people. Do you have any languages? If not lots of time to do a little learning.
Best of luck!
(I'm a little jealous that you have a blank map in front of you that you get to fill)