Go on then... advise (sell to!) me

Hello,
I've got to say, your site seems to be one of the clearest around when it comes to mattress buying. Bravo.
I currently have a 6-7 year old pocket sprung with memory foam mattress. It's now got some signs of sinkage and I'm feeling minor back discomfort when waking up. It cost around £550 when bought from an independent person who seems to try and get good value mattresses from non-major brands.
Quick info:
1. Two people sleeping on the bed - me and the wife.
2. I'm around 86kg and the wife 87kg, and we're around 5' 10" so a little overweight but nothing extreme.
3. Budget is around £1,000 and can be a little flexible in both directions.
4. We have a European/Ikea King size bed, so would like to use the extra 10cm width compared to a UK King size mattress if possible.
Based on our experiences with hotel beds, ones that seem on the firmer side seem to result in the best sleep. I've no experience in saying what makes it firm though to be honest, and I reckon you'll know better than us what we actually like.
I sleep warm, the wife sleeps cold, which is a bit awkward. Generally, she needs one extra layer than me, whether that's clothing or a duvet. We're both quite fidgety and I'm woken up very easily, so movement resistance to the other partner is important.
Would love your recommendations and considering everything from pocket sprung, foams and latex.
One thing as well we don't see mentioned much is the Eve mattresses. I like they have EU sizes as a standard, and they claim that, "We have developed a memory foam that has both the beneficial properties of latex and the extra comfort of foam". I can't complain at the price too and would welcome your input or any danger signs there!
Thanks so much.
Marc