Just for a reference, I'm Qantas Gold (Oneworld Sapphire) and was flying BA in business class early Dec from CDG to LHR and was not allowed to use the AF lounge. Even though they allowed paid access, they wouldn't let me in, even as a paid customer. I'm not sure if this is correct or not
AIUI, paid access is for members of a Skyteam programme flying AF or KL (possibly other ST airlines?) whose status in the ST programme concerned is not enough to give them access. It is not a general paid access for anyone on any airline like a generic airport lounge might be.