8 months is a great age to travel - assuming not mobile yet
Is your LO in a sleeping bag? you can get cotton/muslin sleeping bags which are great for hot weather.
Mozzie repellent - the ones you want are the ones made with Lemon Eucalyptus (sometimes they have the latin name on the ingredients) - just as good as DEET but non toxic.
Hats with strings or elastic so they stay on
UV suit maybe - although tbh with a non mobile baby you can usually keep them in the shade quite easily so not so necessary IMO
Ultrasun sun cream is brilliant - doesn't irritate sensitive skin, lasts really well and not sticky
Take a sunshade for the buggy
Zoggs (or similar) blow up baby swimming seat for the pool
Take your monitor so you can sit outside when he naps
Sling for the airport (in carry on) as it can be a long wait or walk till you get the buggy back. Also good for if they have to nap on the flight.
Will there be baby friendly food? Take some Ellas and snacks in case there isn't much available, or for eating out.
Stacking cups are a good multipurpose toy
A ball of some kind (though you will be able to buy one there v easily)
Nappies - we tend to take enough pampers baby dry for the nights (as they are reliably leakproof) and then buy local ones for the day, cuts down on baggage space
Lots of muslins, wipes, tissues for the journey - easily accessible. Also carrier bag(s) for wet/grubby stuff. Pack in your carry on a change of clothes for the baby and a spare top for you in case of any yuk incidents.
Blackout blind if he's used to blackout at home (unless accom has shutters)