So confused in the search for the perfect natural fibre mattress

My husband and I are looking to buy a new bed and mattress. We're probably going to get a wooden bedstead, so one question is, is purchasing a decent pocket sprung mattress a waste if we don't put on the divan it's made for?
We're looking at pocket sprung and like the idea of natural fibres (often get too sweaty in bed), but given most beds in the shops don't really specify the exact components, we're dubious as to what most of them contain. I'm 5'4 and 61kg, husband is 6' and 75kg, both side sleepers. From trying a few beds in various stores and bensons comfort station, it seems we're more suited to a softer tension (2 or 3 on the bensons scale), otherwise we find our hips/shoulders not sinking enough... We both quick like a soft sumptuous feel on the mattress top. We quite like a few in the Relyon AIS Royal range, the mid price point ones, around 900 pounds for the 1700 Reylon Royal Sandown. Is there any comparable mattresses in your range that we should be considering around this price point? Thanks!