Hi
@SallyToms, and welcome to the forum. The weather in Seville I expect would be good in October - I'm thinking of walking from Madrid next week and my biggest concern is the heat. If you want to play around with looking at average temperatures,
this website is great. You can compare a couple of cities.
The Vdlp is a vastly different beast to the CF. I am suspending judgment until I've walked it all - I started from Salamanca earlier this year but was defeated by plantar fasciitis. Hopefully I'll be able to try it again one spring. In Salamanca I met up with two friends who had walked from Seville, and they were not impressed. They found the stages long and difficult, the infrastructure poor, compared to the CF, and far fewer pilgrims. But other members of this forum, whose advice I trust, absolutely love the Vdlp.
I walked the CF three times before I ventured further afield, for no real reason other than convenience. Each time was quite different - different seasons, different people and I tried to stay in different places. I then walked twice from Le Puy, once in autumn, once in spring, then did two more routes in France before coming back to Spain to the Norte. Since the Norte I've walked the CF again twice - and still love it.