Its important that You are provided a full list of SQL servers and databases on day one.
However once you have these I would always recommend that you go off and check them further.
First compile a list of all the servers given, from here you should check you have access. In a large organisation this could prove to be a hard job. But one you should start as soon as you can.
Now from here you can use some lovely code - post coming - to check though each and see if you can discover any extra servers. Almost all organisations when doing this exercise find that they have servers they did not know about. - More detailed post on this to follow - This is maybe due to the fact that they are never used, or are on peoples desk tops, or out of normal servers naming convention. But they all need discovering and reporting on. One of these could be really important to someone.
Go to each one and use OSQL - L. This will find all servers on that subnet. I will post later on a more straight forward way to do this.
Once you have got all your servers, now you need to list all databases on them, from here you can start to work out the environments and SLAs. More on that Here