Three hours is the minimum for being able to claim delay compensation of 250€, that is based on schedule and actual doors open in MAD, not departure time. At some point you will probably be able to offload yourself too, and get a full refund, though at least technically that is after 5 hours, so this is best done in careful liaison with the turnaround manager or senior cabin crew member.

After 2 hours delay, it is my view that you can take a reasonable amount of food and drink from the M&S OnBoard menu and claim that from BA later. If you can pay with Avios then the transaction would be easy to refund. However note that as far as I know this is untested under the new BoB ways of working.

Best source for information on this, and a lot more detail, is in the Forum Dashboard thread for EC261.