And So To Bed mattress confusion

Hi guys After spending the best part of a day looking at mattresses and being utterly confused, I've just spent an hour browsing through your website and have learnt so much more than I did in any of the stores I visited!

Myself and OH have decided that we probably need a new mattress after continually complaining of stiffness and headaches (though for me, I probably still need to find my perfect pillow match also). Our current mattress is probably about 5 years old, I've not a clue what brand, we weren't very informed when we bought it. It just suited our price range and I was more interested in the nice bed frame. The mattress is one-sided with 50ml memory foam on top. To be honest, I'm not sure what's underneath but I don't think there are any springs. The bed frame has wooden slats (80mm) with a gap of (75mm). Ideally, we'd like to keep the frame. I'm around 55kg and have slightly weak bones due to chronic illness so often feel pressure around my hips and tension in neck / shoulder. The hubby is around 77 kg. I like to sleep on my side and he on his front. We visited 'and so to bed' where the advice was I should go for soft, my OH medium. After checking out a few, I wanted to just take a nap on the Vi spring Shetland there and then. I always thought I needed a firm mattress (why??!) and it was like a revelation lying on the Shetland. After that we visited John Lewis and found a few of their own range which seemed ok. Then we came across a Vi spring Marrister which appeared to be very similar to the Shetland and was on sale (the display model) at £1750. The sales guy then came along and said he'd give it to us for £750 - bargain!

We weren't sure as it was the display model but it seemed clean enough and were just about to go for it when we realised it was a kingsize - our bed frame is a double. Gutted. Anyway, back to drawing board and that's when I came across your website. I wondered what alternatives you might suggest that meet our needs for a wooden slatted bed frame. In terms of budget, we'd probably not want to go above £1500. Also, I've been reading about slatted beds on your site and it looks like we'd probably benefit from putting something between our mattress and the slats?

Thanks in advance. Fern >