France or UK in Oct

Am plaaning on going to Vendee next year ut before this I have the kids for most of the half-term end of October. I could possibly get a late ferry and stop over the other side near to the port and then travel down toward Nante Saturday morning. We would need to travel back on the Wednseday with a stop on the way arriving back Thursday PM. And so questions;

1. should we just stay in this country due to timescales?

2. Give it a whirl even though we only get 3 full days on the site?

3. Are there going to be sites open until 2nd Nov? - I think they are