Hi Mathieu,
I'd head to Geraldton if I were you rather than Lancelin as October is just a fraction early for constant seabreezes in Lano but they should be in and happening pretty good in Gero.
There is a caravan park across the road and slightly downwind of Point Moore which is the main riding spot in Gero.
There are a few riders up in Gero that I am sure can give you more info. However, being without a car or van will make you spot choice rather limited, not that there is anything wrong with Point Moore, it's one great place with both smooth water and also waves out the back.
Good winds,