Shower Doors For Sale Basement Planning Permission?

Basement planning permission? - shower doors for sale

I have this question before, but decided again to ask for further information.
I am interested in buying a house with a basement (the basement is from outside the house in the backyard with a PVC-U door and the basement is accessed from the accessible "in the interior of the house with stairs to the basement.)
In the basement there is a PVC-installed windows and the basement has its own shower with WC.
the current Seier said it was like that when they bought the house 5 years ago and everything what they do is decorate and dry ling a patch of moisture under room install window also has a power point on a wall inside.
I know I should have (a building permit for all this and not involved in an extension of the property was), I request that my house sold is coming closer and advice completetion request takes weeks for a response.