My understanding the tours are all in Spanish although we secured a free ticket and used the English brochure provided which is probably adequate as it is more visual than anything else. The free tickets are limited to 50 per day and are available (with ID) at 7.00 PM the night before the visit from Number 3 in the small street (green window) south of the main entrance of the Cathedral just three doors down from a Cathderal Gift Shop.The people in the Museum and Gift Shop will tell you where.

El precio general son 10 euros. Hay entradas reducidas para mayores de 65, estudiantes o peregrinos de 8 euros. Los niños menores de 12 años entran gratuitamente.

Non mi risulta che si possa prenotare.

No, no está permitido tocar ni realizar fotografías.

Actualmente no es posible realizar esa visita debido a los trabajos de restauración. La fecha prevista para la finalización de la obra es finales de 2017.

I can't give a definitive answer, but when we were there we were advised it was not possible to see it.