Latex mattresses are a lot warmer than standard sprung ones, as such a different approach to bedding may be needed. We find the kids are comfortable in winter with a summer weight duvet and a cotton waffle blanket. In Summer the waffle blanket is usually enough on its own (with a sheet of course!). I've not always been thrilled with the quality of cotton waffle blankets available to me in NZ, so I decided to convert the lovely cotton waffle cot blankets into a single blanket.
I simply machine stitched the two blankets together.
When they are under the duvet no one can tell it is two blankets sewn together!