CI and electronic patiend record app

[eluser]Unknown[/eluser]
Hi,
I was landed with a project involving an electrinic patiend record.
We have a software that manages the patients based on Inoformix that is lacking the epr functionalities.
My boss decided to implement these new functionalities and I suggested the use of php and mysql, accessing informix data using odbc.
Since there will be only me working on the project I am looking at a way to save time and was wandering if CI could be right for me.
I have knowledge of php and sql but not a big knowledge of OOP even if I use adodb classes and complitely new to framworks
Also a big part of the project will be authorization (I was looking at liveuser but it seems quite difficult and not very well documented) and I understand that CI can use FreakAuth lite.
How long will it take to learn CI (considering I could spend 4-6 hours a day doing this)?
Was also looking at cakephp but it seems more complicated even if there is ACL built into it.
Thanks and excuse me for my long post and my poor English
Luca