Damp cottage, renter's rights?

[u/AdventurousDog168]

Cornish terraced cottage, 2 bed, rental, occupied less than 1 month. Damp issues, and heating issues. How stuck am I?

The main problem with the house is the smell of damp.

I agreed with the agent's assertion upon viewing that it will probably clear when the house is ventilated. This has not been the case after almost 3 weeks of constant ventilation. 

No mould is visible. The smell is worse in the morning and mainly perceived downstairs. It is an ammonia type smell which cannot be healthy. 

After ventilation failed, the next step is to blast the heating for a few days. This had not been possible upon occupation because there was no water in the hot water pipes, and the heating system wasn't functioning. 

The hot water was in fact simply switched off at a small valve in the system.So this was rectified on 26th Aug and we regained hot water , but this gave rise to a leak in the system which was causing an overflow from a pipe into the garden of approximately 105 litres per day (i timed and measured it), which was draining into the foundations. Radiators were only able to get lukewarm after 3 hours. I shut everything off and switched off the inline valve to reduce the outside leak. 

Neighbour tells me previous tenant moved due to high water bills from the unfixed leak. I suspect it was draining into the foundation for months unchecked.

The heating engineer attended on 3rd september identified a leaking valve at the immersion which when fixed will stop the overflow pipe leak into the foundations. A new part was ordered Thurs 3rd Sept. I continued to use the hot water system as directed and tried to heat the house to tackle the damp. 

The Mitsubishi heat exchange heating system only allows the radiators to get lukewarm. The heating engineer insists this is normal operation as it's only trying to increase the room temperature by a couple of degrees. 22 from ambient 20. I boosted it to chase 29 degrees,  then was told it not going to get there,  it's designed for 22 degrees room temp. To me this system is either not fit for purpose or faulty,  but even if not the case , it means we cannot blast the heating at full heat to dry the house. 

The next day I heard a leaking dripping in the cupboard from the faulty valve onto the floor underneath the emersion heater , identified a puddle beneath it and I turned off the water at the inline valve, tried to catch the drips in the cupboard and noted that the drip in the garden side was still continuing.

I reported this to the engineer and agent. No immediate reply. 

Upon occupation I realise that there is no heating radiator at all in the kitchen (tiny kitchen in single skin extension around the back door) and the bathroom has no rad, just the towel rail which is not activated by the heating system and it must be switched on in advance with the fused switch. Two of the radiators in the house do not have a thermostatic valve control.

The wall mounted temperature selection unit downstairs seems faulty as the display disappears/ unpowers itself and may be contributing to lukewarm radiators by giving the wrong temperature. The upstairs digital controller is used to program separate water and heating schedules. There is a 24hr timer also, inside the heating cupboard which may or may not be required switched on for the other controller to work effectively.

Today is day 18 of occupation.

Leak unlikely to be fixed until Monday- day 21 of occupation. 

I'm told the immersion needs heated before rads get hot. This will mean it takes ages to heat the rads from a cold immersion and will surely cost a lot on an ongoing basis. Winter will see the unheated bathroom and kitchen leech out any heat we manage to build up in the house. We'll be heating the moist air of the damp ground floor area before benefitting from ambient heat. Any wet in the foundations will only be added to by the autumn and winter months. 

The outside was painted within the last 3 years. Non breathable? Previous work was completed on guttering to address damp in the upstairs. Stains remain.

I anticipate both heating and ventilation challenges in the coming months. Wife and I both work from home and will spend 90% of our time in the damp ground floor area.

What level of damp inhalation in acceptable for the agent/ landlord to expect us to endure?

When does it become unhealthy? What remedial work can be insisted upon?

I can't face the circus of finding another rental property. This took 2 months and we were lucky to get it. It's perfect for kid's school. There's parking. Shops near.

Do i have rights to leave without notice in first month given the issues?