No.. You can engage with only one module...
See, In SAP, all modules are little bit integrated with each others..
Like for MM, it is integrated with SD/FI/WM/PP..
So, one will be your base module and others can you your integrated modules.
and about the education center..
Its depend on your quality...
You can join these center which is lesser price...
Just know about sap.. As this is your learning period, I suggest anyhow just enter into SAP world, then you will know about these all things...
Find just a source for entering SAP world...
Once you enter the SAP world.. You can do the certification course...