I think the fundamental problem in this thread is, you're unable to understand and come to grips with just how few rights tenants have; you feel the Government should be there to protect you.
Think of it like this: the Government, and courts system, are just like a Human Resources department of a massive corporation.
On your first day, they meet with you and tell you that they're there for you, they hand over a bunch of policies that say you should let them know if you have a disability so they can find a way to accommodate you, they tell you they don't tolerate bullying, and they make you think they're your friend, and anything you say is confidential.
That's not how it actually works once you scratch under the surface. You can be sure someone in HR will be on the phone to your boss the minute there's a whiff of a problem but nothing will ever get put in writing, so you'll already be on the backfoot, because now your boss knows. The two disability forms my OH filled out for x2 massive employers and HR contacting him to accommodate them? No, nada. HR are there to protect the corporation, but you'll be sure they'll be your best friend if ever there is a hint of a scandal.
The Government and courts system work in a very similar way. They get money from businesses to run the country and rely on that; they don't want to upset businesses. Perhaps some examples may help:
It's written in housing law that a landlord must provide you with working heating and hot water.
But there's nothing that says 'at all times.'
So, your boiler breaks, it takes your landlord all winter to fix it, that's just tough shit. If you feel he's not meeting legal requirements, you have to fork out the money to take him to court.
But then what happens?
You get a Section 21 eviction notice (a 'nobody's fault' eviction) and have to find a new home within 2 months.
Then the landlord refuses to respond to reference requests from a potential new landlord and because potential new LL is prudent, they refuse to rent to you.
Or
The heating system must be maintained every five years.
But guess what? Nobody does, there's no paper trail given to tenants, there's no 'renters checklist' that shows you your radiators should be fully working because they were last tested 2 years ago. Freezing cold radiators? Tough shit. I had engineers lie to me for 3 months that it was NORMAL that radiators be cold at the bottom, like I was some dumb f**k who just crawled out of a swamp and didn't know how to google.
Guess why I didn't push and push and push it?
Because I knew I would get a Section 21 and didn't want to be forced into moving in a timeframe I have no control over.
It's a disgusting fact that 40% of people who complain to their landlords about repairs get issued an eviction notice. And this is perfectly legal.
This should be banned, right? The Government should protect you from that?
Well, the Government proposed a Renters Reform bill around about the time they were last tarting for our votes and now, 5 years later, the house of lords keep sending it back saying 'that's not good enough' to the house of commons, but the house of commons get the final say on it, and about a third of the backbenchers who are opposing the part of the renters reform bill that bans landlords from evicting tenants for no reason are also landlords themselves. So they're just sitting there arguing about it.
Another example:
LL must provide affordable heating system (paraphrased)
But guess what? There's no definition of 'affordable.'
If they really cared that much the law would be very specific, i.e. 'the landlord must provide a heating system that costs no more than 10% of the disposable income of the median salary in the area' could actually do something.
Again, the Government should sort that, right? After all, we all want to go green.
Again, the Government paid lip service to that. They announced that as of 2025 all rented homes must be an EPC C or above.
.... and then they cancelled it.
Turns out, they hadn't thought through the costs of doing that, the lack of workmen available to carry out the work, or the droves and droves of landlords who would say 'sod that, I'm selling up' - which is exactly what was happening up until six months ago when they went back on their word. All the really old, energy efficient rentals were just getting sold.
So. Anyway. Think of the government and courts a bit like a sly Human Resources department and perhaps you'll start to have a better time. Or at least a better understanding.
As to your current tenancy, do you need a rental reference for your next house? If so, tread carefully. Don't push your landlord. I've moved three times in three years and the hoops you have to jump to are getting progressively worse. I can also promise you it matters jack shit how much money you have in the bank or earn either. The demands before they 'let' you rent a home these days are completely intrusive and out of control.
So, if you need a reference, you really NEED a reference. And that should be your first and top priority.
As to the headaches: yeah, mild gas inhalation will cause headaches. I doubt you will have permanent harm. True carbon monoxide poisoning will kill you in your sleep whilst you are sleeping.
(fun fact - the reason that gas smells is because they add chemicals to make it smell cos it's so dangerous - gas naturally doesn't smell of anything)
Make sure your next home has carbon monoxide alarms in any room with a gas boiler and or gas heater/wood burning fire.