Thanks for the replies.
We're on J/Avios tickets (single through-booking) so would be eligible for FastTrack and Business check-in.
How is FastTrack at T1 working at the moment? Given the huge queues and the fact that you can purchase FastTrack, I wondered whether it would have been suspended temporarily?
Will I be able to jump to shorter queues?
One snag might be that 2 out of the 4 of us only have Y tickets on BA1385 as there wasn't availability on the domestic leg. Presumably my BA195 BP will permit FastTrack and lounge access?