There is a myriad of information on the internet, but don't get dragged in to anything but the official guidance and rules.
The Pensions Regulator controls this entire process and is the same government body that will fine you if you get it wrong - so your first step if you want to understand the in-depth workings of auto-enrolment is found here:
http://www.thepensionsregulator.gov.uk/docs/detailed-guidance-1.pdf
The Pensions Regulator and The Department for Work and Pensions have recently launched a guidance website for employers and employees which is a useful summary for those that prefer a little lighter reading.
http://www.workplacepensions.gov.uk/
