Memory foam makes us sweat and disturb each other

Hi. Randomly ended up on your website and you guys seem really excited by mattresses and keen to dispell the bull, so I thought I’d ask you for advice. I tried posting a couple of days ago, but I think I may have added a word to the bull one above, so it got caught in a moderation loop.
Since my wife and I have shared a bed we’ve not been comfortable. We had a memory-foam topped one that made us sweat, then we had a king size millbrook mattress that was quite comfy, mibbe a little soft, except I sleep like a rotisserie (I am always too warm) so I disturbed my wife a lot and she didn’t like that the little toggle things were sharp. We ended up with a Sleepeezee Jefferson 3000 superking pocket sprung zip-link bed and mattress (couldn’t get more than a king up the stairs), which stopped me bouncing her out of bed, but just might be a little hard. I’m about 18-19 stone (mostly evenly distributed rather than just a massive belly) and I frequently wake up with dead arms and a bit of an ache on my hips. My wife just feels uncomfortable. She’s about 12 stone. I’m just over 6 foot and she’s a bit under. I tend to sleep on my side, although I do spin throughout the night and my wife alternates throughout the night between side and back.
Every time we’ve bought a bed we’ve been guessing and wasted money in that mattresses should last 7 years or so and we’ve given up after about 3 then bought something else we’re not happy with and lived with it due to the expense.
Probably the closest thing we’ve had to a good rest is in the updated Premier Inn beds by hypnos. If anything they are a fraction on the hard side, but closer to what we need than what we have. Budget – obviously I’d rather not spend anything as we’ve already spent a grand within a couple of years on a mattress, but ceiling is about £2,000.
We had a look in the main chains and the favourites were the Dreams Flaxby 6500 in their medium firmness and the Connoisseur Supreme in Bensons, again medium, however it's next to impossible to know what a bed is like to sleep on it compared to lying on it for 5 minutes being watched by an assistant and you guys seem quite vocal against pillow top beds and the internet seems quite vocal about Bensons and Dreams. You also mention that a good bed salesperson should ask about your body and how you sleep rather than which bed you like and none of the places we visited seemed to care. One got quite annoyed when we said we wouldn't consider a silentnight bed at all. (The memory-foam topped one sagged dramatically after just over a year and we had a fight with them. About a 2inch drop from edge to centre when empty!)
I'd appreciate your advice on mattress and topper, especially since I'm always too hot and my wife is always too cold. Would like to get a base too as ours is quite fussy and flowery - basic 2-drawer fabric, probably charcoal-ish colour without a lip on the bottom. Think zip and link is necessary as although we moved house since the last mattress - a superking would still be hard to get up the stairs.