Which bed is right for me?

Hi,
I currently have an Ortho Millbrook Bed (pocket sprung) which is about 10 years old and very firm. Given I weighed well over 30 stone for much of that time, the mattress has done well and is still supportive with no obvious depressions but I started to get neck pain a few years ago and so added a memory foam topper which helped relieve that problem.
However, I have since lost weight and am now down to 25 stone and still losing weight (although the rate is very slow). As I have lost weight, I have started getting hip pain and lower back pain which is noticeable when I first get up. I also now sleep on my side (I used to sleep more on my back or front). General advice on many websites seems to be to go with a medium tension bed to address the hip pain (perhaps a 2000 pocket sprung bed (I want a king size)) to reduce the impact on the body pressure points.
I have looked at your website and your reviews which are very impressive. I certainly feel I can trust your advice. I have looked at your Resilience range but have no experience of sleeping on a foam bed and have understood that such beds tend to be hot (I prefer a cool bed). Grateful if you could confirm if this is right and also perhaps suggest an alternative in your ranges that I should look at (if there are any). I actually need a divan bed so will need a base as well as the mattress (I don't need a headboard).
Grateful for any help you can give.
Many thanks
John