I think you might get 4 months free from bt if you do it online

quick update: Got infinity installed today, a week late due to BT cockup but at least it's connected now. estimate was 27.5 down, 5.8 up. House off Lawers Drive. Actual speed when connected, BT engineer told my wife was connecting between 38-39 Mbits.
I am away from home at present, not home for a week and half.
I will post further details when i get home.

Those figures sound very promising