When you raised the issues, the LL has shown clearly they will be terrible by not actually responding to some of the issues you raised and simply saying they always have a good relationship with tenants. Telling you that you can decorate isn’t good enough if it is filthy.
OP, without being rude, you sound as if you haven’t really known your rights or what to do before handing over money, and have been taken advantage of by an unscrupulous landlord who has spotted your inexperience. They will be the kind of person to try and exploit you and fob you off and this will be a nightmare.
Do NOT move in. I hope you haven’t done so.
Speak to Shelter who will advise and not charge you NOW for help in drafting letters or emails if you need that help.
Check any contract you have is legal and that you have had the How To Rent Booklet. I would probably expect NOT to be moving in here or the issues to be resolved, so start making emergency plans. Speak to Shelter about what to do if you now have no money as you have given it to the LL.
You should email the LL listing the things that are unacceptable.
You should say that you cannot start the tenancy or move in until those things are sorted and the property is in a habitable state and they have bet their side of the agreement to provide a habitable, unfurinished property in a clean and functional state.
You should say you can wait 7 days for them to do this, but if it is not done by then, you will need to look for alternative accommodation and that the contract will be invalid as they have not provided what is required and you will expect all your money back.
You should say you are talking to Shelter and if necessary will be speaking to the local council. If you need someone to help you write the email, find someone to help you.
DO NOT move in if these things are not resolved.
Really sorry this has happened. Just out if interest, was this a seeming bargain of a property?
Horrible these things happen and it is an outrage, but all LLs are NOT like this.