What is the right mattress for metal slats

Hi there I am looking for a double mattress under £1000 to go on a metal slatted base(I understand you suggestion of hardboard over) and prefer the feel of an open spring mattress for its lifting-up feel as opposed to the 'inertness' of pocket springs( although realising they are not the mattress of choice). Not memory foam as it is too warm and I don't like the sinking-in sensation, prefering a firmer feel but not hardness. I weigh nine st four and my husband (who is impervious to mattress condition !) eleven and a half. Can you suggest mattresses from your range that would fit the bill?

Many thanks Sheila King >