Yes we would advise that for a slatted base, it would be better to place MDF down. This would firm up the overall feel of the mattress on the bed.
The mattress choices would then be down to your own personal preference. We would be able to advise you, all we need is your height and weight. From there you then tailor your mattress choice based on how you want the comfort layers to feel. IE soft, medium, firm.
If you have any further questions please don’t hesitate to call through to the office.