Charges under S154 carry 3 demerit points, they stays on your record for two years from the charge date.
It may be in your best interest to fight this charge, because it's one of the more difficult charges to get a conviction under the HTA; the crown needs to be show that the lane change was not done safely.
R. v. Capobianco, 2010 ONCA 589 (CanLII)
Section 154(1)(a) of the HTA reads as follows:
Where a highway has been divided into clearly marked lanes for traffic,
(a) a vehicle shall be driven as nearly as may be practicable entirely within a single lane and shall not be moved from the lane until the driver has first ascertained the movement can be made with safety;