Guidance required type of mattress

We are confused and need guidance please! We currently have a Body Impressions memory foam mattress, double, on a rigid slatted wooden base.
We find this to be comfortable and supportive but I find it to be very hot. Hot flushes and night sweats are causing me major sleep disruption. I have noted that this is not so much of a problem when away on holiday and sleeping on different types of mattress so I have come to the conclusion that our existing mattress is unhelpful and needs to be replaced. I have tried to use a woollen blanket on top of the mattress to attempt to 'insulate' from the heat but that causes the mattress to be very hard and we both had painful joints, backs and ribs as a result!
We need a mattress that will support us both comfortably. I am skinny and boney so shoulders, hips etc. do not like a harder surface. My husband needs good support as his back tends to become stiff. He has had a prolapsed disc and needs to be careful.
I am 5ft 11" tall, my husband is 6ft tall. I weigh 9 St 7 lbs, my husband weighs 17 St 5 lbs.
My inclination is towards 'natural' but am open to suggestions as to what would best suit our needs. I look forward to receiving your recommendations over your various price range of products.
Many thanks!