There are definitely some threads on this on MN already.
I have ordered a Hypnos Wool Origins King Size from mattressman in January - I'm disappointed that it wasn't clear that it will not arrive until March - but that's only an estimate. There are so many similar mattresses - some are in stock and some are made to order.
I found you can't get a consistent picture - there is too much conflicting and TBH biased information on various websites.
www.slumbersearch.com/uk/dreamcloud-mattress-reviews
Is a site that looks useful until you dig a bit deeper and find that #1 rated Nectar and #2 rated Dresmcloud are both made by the same company (Nectar in the UK) - read all the small print about the motives and information on the site - I found I couldn't trace the reviews on this site to the original reviews.
Reviews on IKEA and Emma mattresses never seem to give a consistent picture in all the hunting around I did.
I found reviews in the broadsheet papers useful
www.independent.co.uk/extras/indybest/house-garden/mattresses/best-mattress-review-b2257466.html
but ultimately it was sleeping on a mattress that my daughter brought that pointed me to this mattress. We previously had a handmade mattress from a tiny firm - we loved that but it was like a bag of flour which is what we liked - when we were younger we preferred harder mattresses and really didn't like the softer mattresses in hotels, etc but now we are 60 and having slept several times at my daughter's we decided we would go for a slightly softer mattresses.. and wider... as my wife sleeps like a starfish these days (so we've had to buy a new bed frame). It all depends how much you want to spend too start with.
I've bought 4 Silentnight mattresses from matressonline.co.uk - 3 were top end models and one was a more medium priced and I was much happier with the 3 more expensive ones TBH. These were mattresses for my children and my MIL. Silentnight aren't really one of the glamorous names.
Really you need to sleep in one to have any idea.