It is technically possible to do mirroring with a single server, although you will need to install two instances of SQL Server. Whether you should do this in a production environment though may not make sense!
Mirroring is not something you need to configure upfront when the server is setup. If further down the track you get another server, then you simply configure the 2nd server and set it up for mirroring there & then. You will not save any time by configuring it now with a single server, you will just create more work for yourself.
My advice is that you get yourself a developer version of sql server & install some instances of it & play around with it to get yourself familiar with setting up & tearing down mirroring!