Where are you seeing that offer? The link you’ve provided shows paid tier for Ionity at £6.30 a month which reduces the price to 59p per kWh.
I’ve had my BMW for three years and used the tariff you mentioned which was very helpful, but I wasn’t eligible for the free 12 months as it was a Motability car (just like other manufactures are offering free chargers etc, you won’t get those if you’re making a Motability order).
from 01/02/2024
0.59 GBP / kWh