latex topper on a pocket sprung mattress

Due to my wife being disabled we purchased an adjustable electric bed (2 long small singles making a 5 foot unit). However the pocket sprung mattress which is only two months old is on the firm side, so I was looking to purchase a latex topper, would this be a sound idea??. I am 5. 7" and weigh 11 stone, my wife 5. 2" weighing 13.5stone Can you help with with some advice please.
Cheers
Bob Beckley