I was due to fly from Belfast to London tonight on the last flight, which unsurprisingly has been cancelled in the past hour.
All credit to BA, the cancellation text included details of the flight tomorrow that I was automatically rebooked onto, together with the option to change it to a different flight free of charge, or request a refund. I decide a flight at 06:45 was too early for me, so changed it to a more civilised time. All very easy to do online - something that the TOCs should try and do.