Are all the flights on Iberia? If they are then you will arrive and depart from Terminal 4. The transfer should be easy as it's all the same terminal but bearing in mind you will need time to get off the plane and find the new gate and you will board 30 mins before your next flight you won't have much time in the lounge. The lounge is the Dali lounge in Terminal 4. It's a little confusing as there are other lounges and they all have signs saying VIP lounge so I suggest you ask for directions.

If you're not on Iberia for all flights then all this changes