You are correct regarding Concorde Dining (First ticketed pax/Premier/CCR cardholders) and Club World Pre-Flight Supper (Club World ticketed pax).

The lounge is one single lounge, shared between F/J and is branded as the 'British Airways lounge' (not Galleries branded). Concorde Dining is to the right of reception, the main lounge area is straight ahead with the Club World Pre-Flight Supper area halfway down on the right, at the rear of the main lounge buffet area. There is a small VIP seating room by invitation only, and a small Concorde seating area and bar before the Concorde Dining Room.

The main lounge buffet has sandwiches, salad, cheese, fruit, crisps, nuts, sweets and biscuits. No hot food here.

I was in the lounge (and CW Pre-Flight Supper) a couple of weeks back and have a full photo review coming soon as part of a wider trip report series.