The systems works perfectly fine for AA so I do not see why it cannot work for BA. Never seen an issue why I fly AA.

Its not a special menu; just a standard regular meal. It is really dependant on the crew to set aside the set number of meals once on board and passengers do not move seats without infoming anyone.

Given UK catering, I will be waiting for "I did not get my pre-ordered meal. How many Avios wil I get"