Check MyBT as it now contains a section giving the minimum term end dates for your contracts.
As already mentioned you no longer need a MAC for transfering phone and broadband, you let the new provider handle things. You may though still need to give BT notice to cancel other services such as BT TV, BT Sport or BT Mobile.
For me if I login to MyBT on a PC using Firefox there's a contracts tab I can expand just above the different tabs for my products such as phone, broadband, etc. That additional info seemed to appear a few days ago.
I can't seem to see the contracts info through the MyBT mobile app though.