Flying BA next weekend - which terminal?

[NotQuiteCockney]

We're flying BA to Toronto next Saturday. It looks like this flight is currently from T4, but there's a lot of stuff online about when flights are being moved to T5, none of it very clear.

It says T4 on the BA website. Lots of, but not all, flights have already moved to T5, but next batch isn't due to move till September.

If you are still unsure phone their helpline.

Ah, right, ok, that makes sense. Thanks.