MOS, yes there is a paddling pool and sandpits, here's the text from CF website
"What can I find there?
Coram's Fields has a wide variety of activities including extensive lawns for free play (and very suitable for family picnics), artificial turf sports pitches, a paddling pool, sandpits, a flying fox and other slides, a pets corner (with sheep, goats, ducks, hens and much more), vegetarian cafe, a nursery and drop-ins for under 5's as well lots of other organised activities.
Our aim is that all of Coram's Fields play areas are suitable for use by children with disabilities, including a new sensory play area. There are children's toilets, and those accessible to disabled children and the Under 5's."
You can get food there and nearby but bringing a packed lunch seems like quite a good idea.
Sun cream? Though if you're used to Saudi that's probably a bit obvious sounding.