JByrne,
Welcome to the Forum!
You will find a great deal of useful information in the various Forum topics to help you plan your camino. Everything from the various camino routes, equipment, places to stay, and traveling to and from the camino(s) has been discussed here by veteran pilgrims. Scan the topic headers to get an idea of the wealth of advice and tips available. Use the Search space on the top right of the Forum page to find answers or write further posts for Forum members to answer.
Most camino routes end in Santiago de Compostela; which route do you plan to follow? The most famous is the
Camino Frances which many pilgrims start either in St Jean Pied de Port, France, or across the frontier in Roncevalles or Pamplona, Spain. The
camino Frances is the +/- 800 km route depicted in the recent movie,
The Way. From Madrid there is RENFE train service to Pamplona. See this English web site for RENFE info >>
http://www.renfe.com/EN/. From Pamplona you can take a bus to Roncevalles or St Jean Pied de Port
Anyone may walk the camino. However if you wish to stay in pilgrim albergues you need a Pilgrim Passport or Credential. These can be obtained in SJPdP at the pilgrim office at 39 rue de La Citadelle or in Pamplona at the various albergues, the university and the cathedral. A most useful list of all the
Camino Frances albergues is found here on the Forum >>
http://www.caminodesantiago.me/camino-frances/.
Good luck with your plans and Buen Camino,
Margaret Meredith