New mattress please?

Hello there, we are wishing to replace our 9yr old Sealy Ortho Support mattress... We have done a little 'bed hopping' in the show room... Found one, two at a push- that we thought we suitable...1. Handmade Bed co Grandeur-really like this one!!!! 2. Sealy Geltex Adelaide thought was nice... Liked the idea of cooling Geltex as I tend to overheat in bed. Our credentials are.. Me 80kg...OH 85kg...we have a slatted (no sprung) bed base. I loved the Grandeur mattress it was of a Firmer tension, though tad concerned how I feel about tufted topper but we loved the firm 'but soft' feel. we kind of thought our current mattress was about a 4 firmness rating - based loosely on shops 'guidelines' ..... how wrong were we!! It's more like a 2 in their world. Would very much appreciate it if you could recommend a mattress from one of your collectionss. Our budget is £1200. Thankyou in advance of your time and knowledge