Recommendation, 10 st/18 st couple with differing requirements

Hi, my husband and are at looking to replace our Kingsize divan - it has dual firmnesses so my side is a medium and his is a firm. I am 10 stone/5' 72, he's around 18 stone and 6 feet tall.I sleep on my side or front and prefer a supportive but not hard mattress, whereas he finds hard beds more comfortable. He tends to get warm in bed (whereas I'm a lizard who is rarely hot enough!) so I don't think a memory foam topper would work for us.We want to go up to a Super Kingsize and ideally spend less than £2000. Are you able to suggest a combination that would work for us?Thank you, Jo