Regarding the arrival "terminal" (as craigthemif says, it's one large building with modules named "Terminal A/B/C/D"), from the UK it depends more on when you travel than the airline you fly. Non-Schengen flights go to/from Terminal A in the summer and (this year) to/from Terminal C in the winter. Terminal A is closed in the winter. The winter/summer changeover is a moving feast, Terminal A usually opens just before Easter, though Easter is early this year so not guaranteed.

Your flight PMI-MAH will probably (but not definitely) go from the B gates, this is where I notice the majority of inter-island flights assigned, though have never used those gates myself.

You don't mention if you have checked bags. If you do, you will have to go landside to re-check them (out of the baggage hall, up to the check-in level and IB desks are towards the lower numbered desks, in the 60-80 range IIRC, rarely check a bag). Then go up one level to security. After that you have the freedom of the entire Schengen area to eat, though not a huge range. There is one supposedly higher end restaurant before security (just at the entrance to the left security station, there are two security areas either side of duty free, both lead to the same place) , but I've never tried it.

If you don't have checked bags and you arrive to Terminal C, you don't need to go landside at all, you can stay in B/C/D areas after immigration, (just make sure not to go through the automatic doors leading to baggage claim), turn left or right before that. If you arrive to A gates, it's harder to stay airside after immigration because you usually go almost directly into the baggage hall, though may be possible.