Stingy landlord?

It does not matter how much heating the landlord has provided. It’s the tenant was not happy then he should not have taken on the tenancy. Same with windows. Not enough for you not to cope with ventilation? Do not take on the tenancy.
shelter, damp companies will tell you the same.

How long have you lived there?

I am, quite frankly, amazed at the ignorance of some posts here and the irresponsibility of the tenant(op)
if there is black mould in a property it is lifestyle. NO EXCEPTIONS. Phone any damp company, rontokil, Peter cox. Any company they will tell you the same. Heat and ventilate. There may be water ingress from somewhere but is there is black mould it is lifestyle.
Blockages? Well duh! Should the landlord nip around every time the tenant has a big dump and cannot be bothered to flush? Regardless of how far down this has gone.

this is precisely the reason why there is a shortage of properties to rent. Landlords are leaving the market in droves.

"Unfortunately, we will not be able to cover the cost of the plumber you need to employ to make the property you are renting out habitable. In addition, we will be deducting the rent for the several days we did not have access to appropriate washing facilities from this months' rent. I suggest you familiarise yourself with this document before making such requests in future."

https://www.gov.uk/government/publications/homes-fitness-for-human-habitation-act-2018/guide-for-tenants-homes-fitness-for-human-habitation-act-2018#:~:text=Your%20landlord%20must%20make%20sure,this%20can%20affect%20your%20health.

Also, check he's covered your deposit under a safe deposit scheme.

Blockage issues aside I am fairly sure that legally landlords have to provide some kind of heating for every room in the property, so unless it's a studio with one storage heater then that is a problem that the landlord should resolve. It is impossible to heat the property and prevent damp and mould without adequate heating.

I would definitely suggest calling Shelter for some advice about the heating, damp and mould issue.

You said you didn't know about the poo, but now you did know there was a load of poo there and you shoved it down with a toilet brush?

If you don't have a good dehumidifier running constantly, then you have no chance against mould like this IMO. Ventilation isn't enough - particularly if the air coming in is damp.

@sandyhappypeople the OP has mentioned they tried several different methods to unblock it. And depending on how long they've lived there the landlord had a responsibility to make sure the plumbing was in working order before they moved in.

there is no way to prevent mold buildup with one storage heater for an entire flat. Mold is a health risk and your landlord needs to fix this. Whilst you should clean the shower trap for hair (that's on you), unless you are using wodges of loo roll, toilets should be a able to flush down poo. Is there an odd bend in the pipe? The plumber should really have looked into that.

This isn’t true, I’m a landlord and I’m not stingy. Our tenant blocked the sink by putting fat down it, we called out a plumber to fix the issue and paid for it all.

We did tell them if they were this careless next time then they would be paying.

We also had a damp issue, which cost £2k to fix, we paid for it all, it’s our property so why should the tenant pay.

I do expect them to take care of the house but not pay for repairs, that’s just not on xx

If the toilet was blocked what did you do to resolve?

How long have you lived in this flat OP?
The mould is a landlord issue and regulations are being tightened in this area.
Blockages are a grey area, but assuming you have lived there a while, it is not unreasonable to expect the tenant to pay.

In terms of the heating issues were you given a copy of the property EPC before you rented it? The minimum rating for a rental property is E You can search for an epc here https://www.gov.uk/find-energy-certificate]
If there is no EPC or it's worse than E, you need to complain to your local council.

Then of course you should pay! Keeping bathroom pipes clear of day to day blockages is absolutely the tenant responsibility

Could you get a dehumidifier to make things more pleasant for you
https://www.amazon.co.uk/Ometa-Pure-12L-Dehumidifier-Condensation/dp/B09JWSP39T/ref=asc_df_B09JWSP39T?mcid=0b5b72c6c3b03a49832fd8df5a71092d&tag=googshopuk-21&linkCode=df0&hvadid=697327308845&hvpos=&hvnetw=g&hvrand=8444808178191884334&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9046364&hvtargid=pla-1644124665543&gad_source=1&th=1

The storage heater is your answer mate, move.
Just move as soon as you can. My old house was riddled with mould. This was back in 2015 I'd spend in excess of £70 a week trying to heat that horrible house, yet mould was everywhere. I moved to somewhere with radiators. Never seen a bit of mould in this house and we've been here since.

Agree with PPs about the hair. That's on you. However, the loo might not be entirely on you.

We had a loo that kept on blocking, despite being careful about how much paper we used, and not flushing anything else down it. In the end I called a drain inspection company to put cameras down the pipes to see what could be causing it - nothing.
It turned out the flush had been set to "eco" mode, and so the cistern was only half-filling, which just wasn't putting enough water down to flush the poo away. Cost me £200 to find out it was a simple DIY job to fix (but I got the plumber to fix it, as I'd paid him so much to be there - felt more like I got my money's worth!)

I agree with this. My parents' old house was mouldy. Mostly through a dodgy non-existent damp proof course on the house but the lack of decent heating didn't help either (they also had storage heaters). It was noticeable that the rooms with better heating (storage heater AND log burner) had less mould.

As a quick test, you can buy a cheap thermo hygrometer that tells you the humidity of your home. The aim is that it should be around 40%.

Given the levels of mould OP says, I bet theirs is at least 70%. The lack of heating will contribute to this, but if there's mould on the outside too there is probably a problem with water penetration to the walls too. That is definitely the landlord's responsibility, if so.

We use a dehumidifier to dry our washing and it will take the room from 70% with washing in it, down to 40% throughout the day. It dries the washing quicker, gives me water I can use to water my plants with AND heats up the room it's in at the same time.

They're not cheap to buy, but pretty cheap to run, but it will save your clothing and furniture from any further mould.

If once you've done everything you can to keep the property aired and heated you're still getting mould and the landlord isn't doing anything, contact Environmental Health.

Pour Mr Muscle drain unblocker down the sinks and bath/shower drain and once cleared use a cheapo sieve type things that cover the plughole for the shower. Is he aggrieved if you continued to use the shower knowing it was leaking downstairs?

Never put anything solid apart from poo and loo roll down the loo. Those loo wipes advertised as flushable/biodegradable really are NOT! We had to have the drain guy out recently and he went on a massive rant about them - he finds them (and tampons, sanitary products, disposable nappies) are responsible for majority of blockages he has to unbung. £120 to find that out! 😭

I've lived in a house like that before in the early 2000s, it had one big storage heater in the open plan living/dining/kitchen. The only heating we had elsewhere was an electric bar heater above the bath upstairs. It was less than ten years old and part of a modern development in a Scottish city and had clearly been built that way. It also had a problem with damp.

OP - if you are not heating your home it will be contributing to the damp problem. I'd ask your landlord for a dehumidifier and some oil filled radiators which are less expensive to run than other forms of electric heating. If he's not prepared to buy them either consider buying them yourselves or move out. Living in a damp environment

Mould is a serious health issue. If your landlord is this awful you need to report him and move out.

I'm a landlord so can see things from both sides, but if my tenant blocked the shower with hair, knew it was blocked up but did nothing about it and carried on using it to the point it flooded into a downstairs property, I'd be absolutely fuming with them.

No, I didn't mean to suggest she didn't use her own toilet because I'm not stupid.