(I work for SkyDemon)
in addition to the 30 day trial, it would be a good call to have a look at the little tutorial videos on the SkyDemon website and linked to from within the Help section of the SkyDemon app. Great for getting a starting overview and basic how-to.
Have a chat to other pilots at the club and see what kind of devices they use, since direct feedback about niggles are very useful... Most chaps are more than happy to talk about their experiences, and may even be able to ward you off tablets that have let them down in the past. Typically iPads are more stable and reliable, but if cost is a major factor then focus on android - though bear in mind that for exceedingly cheap android devices you can see wild variations in build quality...