In reply to Wingnut:
I’ve just changed my mattress and here are some thoughts (just IMO/experience); sure someone on here can correct. Apologies for the long post, hope it’s of some use.
Scales and descriptions are manufacturer specific and not really transferable. Eg one firm is soft/medium, or medium etc to another. Orthopaedic though tends to be on the firmer side, often too firm for most IMO, but not necessarily what you need. A firm, or medium firm non orthopaedic maybe better.
More springs does not necessarily mean better (c/w foam, no springs, which lots swear by); it’s how they react and positioned. Some are manufactured with soft edges and reports of folk feeling they will roll off.
The top does not necessarily fail before the springs and other internal parts. The one I’ve stopped using was just a “weakening” of springs where I slept; the top was as new but a visible dip showed the internals springs didn’t have the same rebound ability.
Memory foam - reacts to heat (or so I’m told) so the hotter you get the softer it will be. Heated blankets can’t be used if that is your thing. A lot find them too hot and the latest marketing is to have an integrated top with cooling gel!
All toppers add to depth - you may need new deeper fitted sheets/larger flat sheets to fit.
A lot of mattresses are no turn, rotate only, others are no turn no rotate, and the old style turn and rotate. Take you pick; no idea if it makes much difference to most. Maybe if you are significantly different weight to your partner or such like it might.
Some manufacturers and or retailers now do guarantees for suitability, eg 60/90 days sleep trials or a swap (subject to T&Cs). Worth considering if you really don’t know what will suit you. Ideally find a retailer you can go and try in store as these often show what the wear and changes a mattress will look and feel like after some time. Go back more than once and re try - my preference from a first visit wasn’t on my second as I lay on a different make that I previously discounted as it was described as firm and I was looking for a medium/firm.
Most manufacturers/retailers discount their mattresses at certain times of year. Huge savings can be made if you don’t have to buy on a particular day. I saved some £600 on RRP, by waiting a few weeks. The retailer was open and told me to wait for the 20% off which I did, to then discover a further reduction whilst it was on order. They agreed to match the new price.
BTW, (double) mattresses range from £200 to almost £20000 when I was searching!! Pays your money ….