Welcome.
If you're referring to finding an address to a residential (ie not a company) number then this is illegal in the UK and was discussed in
this thread. If you are talking about finding an address to a business number then you could try
googling it via their search engine.
If you're looking for a number from a business or residential address then you could try
www.192.com or
BT Phone Book. If the owner of that number has chosen to be ex-directory then there is a very good chance you won't be able to get their number.