With most of my flights starting with a NCL - LHR leg, I usually pick up a pasty from Greggs in NCL. The flight allows ample time for the superheated pasty to cool down to just mouth burning temperature for consumption in T5.
Depending on my next flight this can be done anywhere in the terminal from the main area, right up to the CCR.
Not sure whether the staff could recommend a suitable wine pairing for a steak bake however.