Student accommodation -minimum standard bedrooms in basement

HMO Licensing

My grandson has rented a student house with 5 fellow students. It has a HMO license for max 6 tenants (expires in a month). It has 6 bedrooms, but 2 are in the basement (one of which is my Grandsons). I went to visit the house when my Grandson became very ill with a tight chest and cough after 2 weeks. The staircase to the basement bedrooms has headroom of only 5 feet. There is a door to each bedroom on the left and right. In one of the rooms there is no opening window and no other source of ventilation. There is a door that can be opened to the back yard. It is UPVC half solid, half window (non opening) and leads to a steep staircase up to a tiny yard which is surrounded by a 2 foot wall which separates it from the street. The door is very narrow and only 5 ft 5 tall. The steps from the door are riddled with rat droppings and when it rains there is no drainage to allow the water running down the steps to disperse - so it will come into the room. There are holes in the bricks to the side of the steps (for water drainage from the garden?) where the rats can actually be seen and heard. This is less than a yard from the back door. The window is so small and below street level that the room is in perpetual darkness. Three of the walls have false walls added about 6 inches into the room - these have been newly built or painted and hide any evidence of mold or damp. But the smell is terrible and it is making my grandson very ill. I just wonder taking all this into consideration, I cannot see how these rooms can be made habitable and therefore can my grandson and his housemates move to a different house with no penalty?