Sorry, only just noticed that part.

I think the sandwiches, peanuts etc. in the Iberia lounge will be enough to keep you going until you get your CE bowl of pasta or whatever. However, you might want to try some of the restaurants in T4S before going to the lounge. My experiences of Spanish airport food have always been fairly horrible, but I haven't tried them in the new terminal. At least in T4/T4S it isn't at all crowded and you should be able to get food fast. Report back.

It sounds like it is your first time using T4 at Madrid. Assuming you are flying on a BA operated flight (and not an Iberia code share), what you do is after check-in follow the signs to gates RSU. That will take you through security, onto a shuttle train (about 3-4 mins), through passport control and into T4S. The Iberia lounge is easy to find, behind Starbucks. There are lots of shops and eateries in T4S so I would head straight there. Also, they may tell you that it takes 45 minutes to get from check-in to the gate. Do not be alarmed: unless you are very infirm, it will take about half that.