Is there any learning material available for GE Smallworld?

Documentation for Smallworld is typically installed with the software itself, and it was (up to at least 4.2) in Windows Help format. The documentation is pretty good and covers user guides, programming, database administration and so on, but I don't think you'll be able to access it without a Smallworld licence.

I'm not aware of trial versions, although GE or a reseller could give you more information or an evaluation licence. Alternatively, you could also look into doing an official training course where you'll both get to use the software and be able to take home the course manual.

Simply answered. Besides some Wikis and Blog entries there is no documentation freely available.