Dag Jos,
It's great that you are considering a trip to Galway this October!
The Camping Ireland
website mentions the campsites and caravan parks by county. By clicking on each one of them, you can see their opening dates. I have linked the ones
in Co. Galway for you. You can extend your search to the neighboring counties (Clare, Mayo) if you'd like.
Spiddal Caravan & Camping Park for instance, is open until October 31.
Are you planning to visit Galway and Connemara by any chance? What is on your itinerary so far?
Groet,
Antoine