Scroll-able gridview

Hi, not sure if this is the right section for my question, but if anyone can help it will be very much appreciated.
We are in the works of making a trading card game.
What we would like to know is, how do we create a dynamic grid-view with this layout? (4 x 5 stored in json)
Cards will be placed and removed here as players buy and sell cards. Each page will contain 20 cards etc.

http://docs.unity3d.com/Manual/script-HorizontalLayoutGroup.html
http://docs.unity3d.com/Manual/script-LayoutElement.html

combination of those…