Can you recommend a mattress.

I'm looking for king size mattress. Medium to firm support. My husband is about 16 stone and I am 9 stone. I don't want to feel him turn in the bed beside me. I tend to be a very 'hot' sleeper so I don't want a mattress that makes me feel hotter. I have a mild dust allergy so I want material that is dust mite repellant. I like the idea of a mattress topper for comfort....