Unfortunately, The choices I am currently looking at don't have built in 3G/4G.

I like the look of the XPS 13.

http://www.engadget.com/2015/01/28/dell-xps-13-review-2015/

There is a version with Ubuntu pre-installed (i.e. no Windows) with touch screen from US $1,349.00. It is linked to from Dell's Australia page:

http://www.dell.com/learn/au/en/aucorp1/campaigns/xps-linux-laptop

Which then takes you to the US site:

http://configure.us.dell.com/dellstore/config.aspx?oc=cax13ubuntus5103&model_id=xps-13-9343-laptop&c=us&l=en&s=bsd&cs=04

...and it appears they don't deliver to Australia.

The following seems to be the closest I can find in Australia (AUD $1,399.99). although it comes with Windows and antivirus software:

http://www.dell.com/us/p/xps-13-9343-laptop/pd?oc=dncwt5131s&model_id=xps-13-9343-laptop#overrides=dncwt5131s:8~256SSD;33~

Similar laptops (with Windows) from competitors include:

* http://www.engadget.com/2014/11/25/lenovo-yoga-3-pro-review/
* http://www.engadget.com/2014/12/30/samsung-ativ-book-9-ativ-one-7/

This could be a really good option, although it is hasn't been released yet, and I don't see anything about it being released in Australia:

http://www.engadget.com/2015/01/05/lenovo-lavie-hz550-hz750/