Yes, they can tell you. Ask about teh seat configuration on the lower desk in Club World. If they say it is 2+4+2 than you have the new CW cabin. If seating is 2+3+2 than old CW cabin.

However, I specifically booked LHR-HGK-BNE as a return from London to Brisbane (using QF for HKG-BNE sector) and BA did a last minute equipment change, and we got the old config, and I was down-graded to WT since my lower-deck CW seat number did not correspond to a CW seat on the old config. Evenually, after refusing to board until the last minute and one upper-deck CW passenger failed to board, so I got their seat!

So there is no guarantee that even if advertised and scheduled as new CW that you will actually get new CW.

But that said, my last return to BNE was LHR-SIN-SYD-BNE on BA15 to Sydney and I really enjoyed the new CW sleeper seat, and suffer way less from jet-lag when I got home. Wonderful J cabin. Just avoid the window seats with difficult access (ie 12K, 13A&K, 17A&K, 18A&K, 19A&K, 60A&K, 61A&K, 63A&K)

Enjoy your trip,
NM