Desperate here, insomnia is wrecking me

Hi, I’m not sleeping at all, I have 3 other children and I work but I just can’t function. I had trouble sleeping before this pregnancy due to restless legs and was given codine to take before bed. I’ve been assured by my doctor that as long as I come off the codine during my 3rd trimester, the baby will not be affected, so please, no judgement. The thing is,, it’s dealing with restless legs but now my brain just does not shut off!! I have tried every safe home remedies known to man, reading, no screens etc etc but nothing is working. I am at my wits end and depression is settling in. Does anybody know of a sleep aid that I can take while pregnant?? My midwife just tells me to ask a doctor but I’m in the uk and getting an appointment is near to impossible. Please help. So desperate here, I’m losing my mind xxx