I have a route planned (i completed the Irish part this summer from home to Dublin). From Dublin the plan is ferry to cherbourg. Then from cherbourg a marked route to Mont St Michel
http://www.lescheminsdumontsaintmichel.com/spip/spip.php?article54
Then following the Breton route Via Rennes and Nantes to Clisson. The route is then marked by another pilgrim association
https://www.vendeecompostelle.org/blg/wp/
From Saintes there is a choice of route. Saintes is on the Tours route. This has more pilgrim infrastructure. Pilgrim gites are available on this route but generally are more expensive than Spanish albergues.
Alternatively there is a route across to Royan and the Voie Littoral which is marked down the coast to Bayonne. This has less pilgrims and less pilgrim infrastructure but is marked by two more local pilgrim associations who also have accommodation lists.
I am planning on taking a tent to reduce costs. But having walked the Via Francigena in France I am using it as a basis for costs. I am working with β¬40 as a lower estimate of my daily costs, as some days will be less and others more. With an extra kitty in case I get stuck with more expensive accommodation. I also tend to cook for myself rather than restaurant meals. As for people who welcome pilgrims into their homes with meals then it is suggested a donation is at least β¬30.