OK, the seat availability for BRI [Bari]-LGW in different fare buckets is as follows:
J9 C7 D3 R1 I0 Y9 B9 H9 K9 M9 L8 V0 N0 Q0 O0 S0 G0
So there are still a reasonable number of seats, but no guaranteed reward seats for gold card holders (V bucket). It's impossible to say exactly how may but it looks like it will be quite busy.