CX arrives in T2 and BA leaves from T2.
If you check your luggage thru 15-20 min from deplaning to the new gate should be plenty of time.
Even if you need to pick up your luggage you should be able to make it in 40 min easy.
So it all depends if and how long the CX flight is delayed. I used this flight a few times in the last 2/3 years and it was never late, sametimes even 30 min early.