I was out hill walking at the weekend and got talking with someone who has been walking the Camino Frances one week at a time. She was telling me that they are due to start again in September sometime, they had their flights booked – but they were having problems getting from Santander to Fromista.
Most people get surprised once they start investigating to discover how good the Spanish transport network is. The train and bus service is generally of a very high standard and from my own experience they normally run on time.
Any back to getting to Fromista – follow this link to see the time table.
I was making the mistake of thinking that it would be better to travel to Burgos and get to Fromista from there – but no. The best train to get is the train that goes to Palencia as the local train passes through Fromista.
So go to the train page and choose the regional trains. Hope this helps. Let me know by leaving a comment if you need more info.