get a decent pocket sprung mattress your back will thank you in the end, those cheap nasty open spring ones are no good for posture.
there is a big thread here.
https://forums.overclockers.co.uk/threads/mattresses-i-need-knowledge.18569001/page-23
there is a big thread here.
https://forums.overclockers.co.uk/threads/mattresses-i-need-knowledge.18569001/page-23