Hi Sander,
I completed the Camino by bike last June.
From St Pied de Port to
Finisterre.
I'm Aussie and flew into Paris Charles de Gaulle Airport which has a TGV train station in it. 2 changes and 3.5 hours and I was in SPdP. The last change was onto a smaller "local" Train.
https://m.en.voyages-sncf.com
Lastly. Tips. It is amazing but the "Camino will provide".
Go as light in your pack as you can. I saw Pilgrims sending have sleeping bag home, buy a Silk bag liner, you could rely on the Allergies to supple a blanket or take a very lite bag.
I took smart phone and a small camera, each had to have cables and chargers. the phone was also to be my music, I did not use it.
Walk your boots in, do a training week of 20/30km walks each day, you will be doing that for weeks.
The Allergues are clean cheap and friendly, mixing with other pilgrims but take a bit more money and have a few "quiet" nights in a hotel, yes you will need ear plugs.
I used the
Brierley Guide plus the list of Fav Allergues
A selection of favorite albergues on the Camino Francés
Hope this helps
PS
Pilgrims on the Left, bikes on the right.