Darren - welcome to the Forum!
Back in September last year, I posted this comment:
BLISTERS:
This was my 4th camino. On the previous three I needed hospital treatment for severe blistering, which took much of the pleasure from the trek. I have tried all the usual remedies - Vaseline, powder, walking socks, massage, etc etc all to no avail.
This year I decided to use panty liners. If you fellows don't know about panty liners, just ask the lady in your life.
I would place the liner on the floor, sticky side UP, then carefully place my foot down onto it, so that it was at the same angle as my toes - and gave me protection along the ball of the big toe, and across the whole sole of my foot just below the toes. Just position it where you usually get blisters.
On occasion I had to buy the extra long liners/pads from chemists in Spain: the same principle applied, and the ends of the liner were simply folded across the top of my foot. I then put on my normal walking socks.
I am not suggesting for one moment that this will cure everyone's problems. Only that they cured mine. So it might be worth a try.
I also limited my walking distances to average no more than around 22-24 kms a day - occasionally down to 15 kms.
If that helps just one of you to avoid blisters, my time has been well spent.
Buen camino! [Without blisters!]