Ill try that out Jayjay, thanks for the tip.
I found another way, not sure if its the best way, but it worked for me.
At the start of the layout I generate a random number within say 1 and 100, and store it in a global variable.
I set this number at the layout start because I use it to randomize other stuff too.
At the end of the layout, if my number is between 1 and 10, go to layout 1. If its between 11 and 30, go to layout 2, between 31 and 100 go to layout 3, etc.
Don�t know how practical this is, but it does the job and it also lets me decide how often a layout should appear by playing around with the ranges.
In this example layout 2 would be used less than layout 3, but more than 1 because of the chances my number has to land on each range.