I believe that if you have a foam mattress you shouldn't have to turn or rotate it. I find foam very comfortable, but also too hot for me as I'm a very hot person!
I'd recommend a trip to John Lewis to try out mattresses, we've always bought there either during the sale or ex-display. They have the option of returning the mattress within a certain timeframe if you don't like it, though you have to put on a certain type of mattress cover which you buy at the same time.
Shops will obviously try to sell you a base as well as a mattress if they can, but it really isn't necessary as it sounds as though yours is the unsprung type if it has drawers.
Seems it’s now Harry’s uncle - the Earl of Spencer - having his turn at a “tell all” book.
Could Lambeth Palace get it any more wrong?

