In NSW at least I believe prescribers of suboxone are technically not allowed to be prescribing benzodiazepines to their patients. You really don't want to get your doctor in trouble.
I'm not sure about NSW, but this definitely isn't the case Australia wide. At least here in SA, I've known a large number of people (including yours truly) who've been prescribed both, and some who've been prescribed benzos with methadone or other full agonist opioids. I think it mostly depends on the doctor and how cagey they are about the situation - A lot of doctors aren't above saying they can't do something as a way of avoiding a dispute with a patient over whether they
should do it.
There is a fairly even chance you'll die
Let's keep it realistic. Benzo addiction is a serious problem, and cold turkey is, by all accounts, universally horrible and potentially dangerous, but I don't think there's a "fairly even chance" that someone will die from coming off 20mg/day valium. Seizures and other complications are a real risk, but that risk should be kept in perspective.
OP - good luck. You've probably already spoken to your doctor, I hope it went well. Insomnia is a cunt of a problem, I'm only just beginning to get a handle on it after years of work improving my health, changing my diet, therapy, meditation, etc etc. It's something you'll probably need to approach from quite a few different directions over time to make improvement, but you absolutely can make improvement.
For what it's worth, opiates definitely don't help. Short acting opiates like codeine are the worst for this, and I'd be surprised if anyone with a serious codeine habit had a decent sleep cycle, but even longer acting opioids like suboxone will mess with your sleep over the long run. I noticed an immediate and substantial improvement in my sleep as soon as I came off suboxone. Something to keep in mind for when you're ready and able to come off the subs.
You really don't want to get your doctor in trouble. A good doctor who is willing to prescribe this sorts of drugs should not be abused. Instead treasure them and cultivate them. Use these drugs when you need them. Not when you just want to get high.
I'm sure he doesn't want to get his doctor in trouble. I also doubt he's super happy about being dependent on suboxone and benzos either, or all the time and effort and money that went into maintaining a codeine habit beforehand. If drugs were as simple as making the right choices across a purely rational plane, addiction wouldn't exist. I'm not saying potential consequences should be ignored, just that if there weren't other, powerful, internal needs driving addicts, they wouldn't be addicts.