Mattress/Divan/Topper combination to suit us

Hi,
I am 5'10" and 13 stone, my wife is 5'0" and 8 stone. We currently have a memory foam bed on slats which I find too hot to sleep comfortably and the bed is a bit old now. We both like a firm mattress. I have my eye on the Artisan Bespoke Zip and Link Medium/Soft with bonnet coil artisan base. Is this going to feel firm for us? Should we also consider a topper? I am concerned that it would make the bed too hot again if we have one.
Kind regards