I have to split the content of a column into 2 differents columns using the QGIS Field Calculator. Basically, my table is something like that:

Basically I have to work with descriptio column omitting characters from 1-12 and then copy next 8 characters (in this case "AgilisSi") into the PresLACAGI column.
The other element to copy is the final number in descriptio column, ranging from 1 to 3 characters. Possibly the best is thing would be a syntax that reproduces in CodiClapa column the number after ": ", including the space in the syntax.
Thanks a lot!