CHOOSING A 4FOOT 6 INCH MATTRESS AND A NEW DIVAN

I am a man, weight 10 stone, height 5feet 7inches. I start to sleep on my side and suffer from coldness in bed, probably due to poor circulation.
My wife weighs 7 stone 8 pounds, height 5 foot 3inches. She starts to sleep on her side and suffers from back pain on occasions
We are not sure about the pros and cons of latex and foam. We tend to prefer natural fibres against man made fibres. Could you please advise on the differences
We also prefer pocket springs to prevent disturbance on either side of the bed
Which mattress should I buy?
What kind of divan do you recommend?