Fixing a Desk to a Wall and Which is the Best Method? General problems, solutions, information and advice on fixing to walls of all kinds

[MRF]

Hi all,
I am filling in a gap between 2 cabinets to create a desk of sorts. The back of the desk is against an exterior wall. I thought about using some large 'L' shaped brackets to hold it up as I have 2 legs for the front. The brackets will be attached to the exterior wall. How would I go about attaching the brackets.
Any help would be greatly appreciated.

[welsh brickie]

fix a wood batten to the wall first, then either drill through the cabinets directly into the batten, or use the brackets