advice for England.
Yes, OP, you have been clueless and as a result I am afraid that you have been royally shafted by your unscrupulous landlord. Which is no excuse for the landlord's behaviour of course. Yes, it was 'sold as seen' but it looks like there have been many illegalities here.
It has been illegal for some time even to offer a property for let or sale without an EPC. If the EPC is below E then it is (as of 1st April) illegal to rent it at all unless it is subject to certain exemptions. Fine for landlord is £4000.
without it you can't be legally evicted under a section 21. There are also lots of other requirements to evict you, all of which are detailed in the how to rent guide on gov.uk. Which you should have been given. There are quite a few incorrect posts on here which I CBA to go through - read the how to rent. There may also be safety issues: gas safe cert (if it has gas). Smoke alarms? And then there's deposit protection..
Environmental health are probably the best bet as that will also stop any eviction once you've had a complaint upheld.
as always, why you want to stay in this shithole which isn't even a cheap shithole is beyond me. If you do, read up your rights and decide what you want to do. Any kind of eviction will now be the best part of a year to the bailiff, especially if this is London.
fitting carpets to a private rental was, I'm afraid, not smart. Only council properties expect you to do that.
get clued up on your rights for the next property - because the only way to deal with slumlords is to stop paying them by leaving. Good luck.