Hi Stella
I have done 4 Caminos all solo and I have never booked ahead. It leaves me the freedom to do exactly what I feel like each day without the pressure of having to be somewhere for the night. That said I have never booked a flight back to the UK until I have arrived in SDC as again this takes time pressure of me. As I am retired this is fine for me but your situation may be different. Just 3 years ago this week I arrived in SDC having done the Camino da Costa. On days of good weather, it is a beautiful journey but beware of the rainy days, it was also my wettest Camino as when the storms come in off the Atlantic, they are of biblical proportions. I always warn people to keep their wits about them in Vigo as the signage both in and out is poor and the town is busy. It is worth the effort thought to see the old town and port. Don't worry about walking alone it is safe and you will very quickly meet up with lots of fellow pilgrims who you will encounter at various times on your journey.
Buen Camino
Vince