I've mapped out so many routes while dreaming of my next camino! From my own notes, based mostly on Gronze. I see a few options:
Toulouse to Oloron St. Marie to St. Jean: 14 days. (
Voie d'Arles & La Voie du Piémont Pyrenéen) )
Oloron to Puente La Reina, nine days. Meet up with
Camino Frances. Then maybe 25 days to Santiago. (
Camino Aragonés). I'm looking at doing this for my next Camino, though I'm not sure. It is more solitary from what I hear. Maybe not the best choice for your first. I'll defer to others who've wlaked this.
Aire-sur-l'Adour to St. Jean, 6 to 7 days (
Chemin de Puy)
Bolded because I've done this, and it would also be my recommendation based on the time you have. There's a train station, so Aire is easy to get to. There's a lot of pilgrim infrastructure in the towns you'll stop in. You see the wall of the Pyrenees in the distance, slowly getting closer each day. The food is so excellent, and you'll eat at a communal table prepared by your hosts each night.. You'll walk through Basque Country. And you'll be in better shape when it's time to climb that mountain!