Ikea - you can buy different thickness mattresses - we went for the middle one and its great for our occasional use - very comfy

Try M&S. We have one which is pretty comfy and wasn't that expensive. Certainly a lot less than £600. They always have furniture offers on and if you're open to buying from discontinued fabric or shape even better. Staff are usually good at telling you if you ask when the next offer is.

We're looking for a good quality sofa bed, as my Mum will be staying 1 night a week with us and she is not a spring chicken anymore.

We're not keen on dfs (heard bad things), john lewis ones don't seem to have machine washable covers....all the ones I've looked at seem to have incredibly thin mattresses. Now stumped, where can we buy a good quality sofa bed (dh is thinking of spending no more than £600)?