If you want to use a travel service, you can of course do so, but it is not necessary. Most pilgrims do not stay in hotels but albergues (dormitory style accommodation) and there are many to choose from. But there are hotels and similar places with private rooms also. Whatever accommodation you prefer, you can easily book it yourself. For private rooms in hotels, pensiones ect. it probably makes sense to make reservations before you go (there are less beds available than in the dormitorios) but if you're more flexible with regards to where you'll sleep, you could also just walk and see what happens, and call places 1-2 days before to make sure you'll have a bed.
From what I heard, the hotels chosen by travel tours are often off route, which is probably a bit annoying. If you make your own reservations, you can be sure you'll stay close to the Camino.
A good ressource is gronze.com.
Bienvenido a Gronze, tu Guía del
Camino de Santiago: Información práctica, actualizada y participativa de los principales Caminos de Santiago.
www.gronze.com
Backpack transport is also easy to organize on your own, for a reasonable price. I have never used it, but other forum members will surely explain to you how it works.
It sounds like you'll be walking the last 100km or so?
If that's the case, don't worry too much. infrastructure is good on that section.
An albergue bed should be ~8-15€/night, not sure about hotel rooms. Backpack transport should be ~5€/day.
Happy planning and buen camino!
