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.