Couple of things, firstly you’ll likely be due some compensation via UK261 depending on arrival time at final ticketed destination.

Don’t cancel anything proactively yourself and don’t agree to cancel for a refund if that option is given to you. you lose all your leverage if you do.

BA as the operating carrier are on the hook to get you to your ticketed destination and pay reasonable expenses including hotel and food. See the disruption thread already linked to.