Hi,
The place you are planning to visit are quite family oriented so you should find everything you need in local stores (same standard and probably same brands as in UK......you are still in Europe!! so no worries for nappies, toileteries etc...)
Just take 24h supply so you don't have to rush to the store as soon as U et there.
As for food, you will find jars. As I said before, Spain is in Europe so babyfood is regulated, no worries there.
I also had a guilt trip RE giving jars only during holidays as baby mainly feed homemade organic food, but it is sometimes just safer than ordering puree in hotels or restaurants. Especially at lunchtime when you may worry about food spoling due to heat.
Evenings, you can ask for purees at hotel, just ask thm to heat thouroughly and let it cool before feeding.
Otherwise you can buy things like bananas, yogurtetc... locally.
BUT make sure you take baby rice with you. Continental euros mainly have wheat based baby cereals and theymix it with milk in the bottle.
I suggest your own buggy (never seen buggy hire anywhere)+ baby carrier for use in airport (and on the beach) to allow you to keep your hands free.
Finally, I strongly suggest taking Milton sterilising tablets + detoll wipes to keep baby equipment clean.I used to buy a cheap large plastic bowl upon arrival and use it for washing and sterilising bottles, feeding accessories etc...everynight so you have clean stuff for the day.
PS: B4 U go ask hotel if they can provide cot/bed sheets/bottle warmer etc....
have a great time.