Actually the suite is larger than that. (They add adjacent rooms to it during State Visits). Basically, the suite begins from the pool (in the Northwest pavilion) and continues toward the Bow Room in the center of that block. Rooms across Marble Hall (like the Billiard Room) or even rooms on the other side of the Bow Room (including the old household dining room, now used as a cinema I think) may also be added to the suite if needed for a major scale visit with lots of officials or staff in the guest entourage.
The 1844 Room is used as the principal audience / reception room for the guest. The narrow Cavernon Room (under Royal Closet), the 18th Century Room, the Orleans Room and the Spanish Room are all included. The Orleans' Room is the main bedroom, while the Spanish Room is sometimes used as a guest dining room, dressing room or other bedroom as needed. The other rooms can also be furnished as sitting rooms, dining rooms or bedrooms as needed (some state guest spouses prefer separate bedrooms, or bring children).
You're right - the 1844 Room and Cavernon Room adjoin directly to the Marble Hall (no Belgian Corridor access). But the 18th Century Room, Orleans Room and Spanish Room all open into the Belgian Corridor, directly behind (north) of the Minister's Staircase. It is quite narrow and on my floor plans don't look much more than tiny hallways. At the end of the corridor appears to be the suite's bathroom (next to the Spanish Room). But I suppose these old plans of mine might not reflect current configuration.