Confused which one to pic

Hello,
I have been looking at the Artisan range but first let me specify what I feel that I need. Me and my Hubby have weak backs and have been wanting a medium firm mattress that gives good support for our lower backs. We used to have a Relyon Mattress 1400 pocket springs with memory foam on top of it which was good except that my husband would wake up warm. The bed is 5 years old and we want to change it.
We are looking for something similar 2000 pocket springs with something on the top essentially so we dont feel the springs. We dont like a very bouncy bed either.
Is there a specific range that we should be looking at ?
Thanks,