I got the opposite, i'm on 10mb now but uplift is only 2.9 with fttc (also cant get it until end of june or later) yet the bt wholesale website and tester says i'll get 75.6mb
You will get what you get and that's that really.
No use anyone trying to predict what you will get.
If the line checker tells you 30mb then that's way better than what your getting just now, anything more than that will be a lil bonus for ya