Thanks for the link.
I tried Floyd's suggestion before seeing the post of inserting a sliver of rawl plug into the hole then carefully tightening the screw, it seems to tighten and engage with the fin. Not sure how it will handle the stress of sailing though, only a temporary fix for now.
As Ola suggested I won't be doing anything too elaborate until some feedback from where I purchased the board.
I'm thinking a slightly larger guage screw may be the only remedy, unless permatex or loctite bonds well with the plastic fin box.
The length of the threaded hole is approx 7mm, and the screw is about the same, so there isn't much material to bond to.
Still waiting for shop reply.