Ignore this poster, what a sour puss. This age is the easiest age to travel with babies before they're weaning and before they're mobile! You'll be on holiday so routines-shemes. You've booked AI so you won't have to think about food or washing up or food shopping or meal planning etc etc, which will be a holiday in itself.
If baby is EBF, then BF for take off and landing.
Travel pram with a carry strap for beside the pool naps, but also take baby carrier. I was much happier and felt safer with baby securely in the carrier on me than lolling around on my lap for coach transfers.
Take laundry detergent sheets like Dr Beckman magic leaves so you can handwash baby clothes very easily in the bathtub or sink if needed, and a travel pegless washing line like Lifeventure Adjustable Elastic Travel Washing Line on amazon.
Take as many nappies as you can, and lots of short sleeve vest babygrows. And muslins. Then pack spares. Travel changing mat with you on the flight plus a spare top for you as well as baby change of clothes.
Biggest floppiest sunhat you can find for baby.
Swim nappies and swim gear.
Take a few select toys that can have multiple use like stacking cups- good for bath play as well as general play.
Take turns with your DP to get some time to yourself each while baby naps. DH used the gym and hsd a beer by himself on his time and I went for a swim or lounged with a book and a cocktail for mine. We built this into every day and it was bliss, you start to remember you are not just a baby-parent.
Spain was a dream for us when we went, and we hate AI. But when your in the baby trenches, it's perfect.
Enjoy your holiday!