properties disrepair and partner living there without permssion

Maintenance

I went to do a property check this weekend and was gobsmacked at the state of property and how its deteriated in 12 months, carpets filthy (black in places, carpet beige) in hall,landing stairs, walls all wallpaper full of dirty black marks and cobwebs. Bedroom door missing due to repositioning of bed as they wanted to watch tv on a different wall and couldn't open door due to this. 2 TV's drilled onto walls without asking permission in lounge and bedroom. Bathroom and toilet filthy dirty. Stickers all over fitted wardrobes. 2 window handles missing. (new d.g.windows 3 years ago). Fitted kitchen cupboard drawers broken due to children she said climbing up them to get to top cupboards.Partner has moved into property and this is when this all started to happen, neighbours complaining about his behaviour. No 1. Is there a letter I can send out re cleaning and getting the property back to its original state without it jepordising anything if I come to give her notice (she now has 3 kiddies)until benefits starting paying me direct we also had rent arrears and also can I insist that this guy moves out as on the contract its just a tenancy for herself, no boyfriend? RLA Tenancy agreement.Have you a template of any kind that could help me word a letter to her regarding the state of property please and me wanting her to bring it back up to scratch and also re not letting her partner living there.