Hi there Roz. There are 16 beds in the Salamanca Albergue de Peregrinos. During Holy Week this year I stayed overnight there, on my way to begin walking from Astorga back down to Fuenterobble de Salvatierre. Salamanca is hugely exciting at this time, with processions every day, music,and fiesta. Some peregrinos stay more than a night in Salamanca at this time using cheap alternatives. There are hostels and also rooms for about 20 euros in the city centre. If I remember rightly, the next village after Salamanca has a small refugio (3 euros? ). You could always arrive early in Salamanca (it is only 18 kilometers from Morille, or 24 kms from San Pedro), spend the day enjoying the sights, then walk in the late afternoon to the next village.
Zamora is a large, new albergue. According to the tourist camino guide which I used when walking, there is a refugio or albergue in the village after Zamora. I didn't stay there, however.
Hope this helps. Regards, Lovingkindness