Do you think we'll come unstuck at the international lounge as our flight is codeshared with Qantas however our ticket has a FJ, not QF?
Specifically our flight is FJ910, codeshare QF 3869.
Unless OP is confusing P+P as paying with points?
I think the OP is a little confused as to what 'codeshare' means in this context. Yes, the flight has a QF codeshare available. But no, the OP is not booked on it. And you need to be booked on the codeshare to be able to use QP benefits as per the QF site.
I assume he got in to the QP by good fortune, but shouldn't be expected.