You don't need to skim the head unless it is warped. Or the gasket mating surface is damaged.
As rich said you need to check it, use a decent straight edge and using it across 3 axis on the head determine whether or not it is warped or damaged, Heads dont normally warp unless overheated.
I think its a crap gasket to be honest, has the head ever been off in the past for work?
I'm assuming it has as your car has a 2 litre bottom end so was it fitted with a genuine gasket or a pattern?
Pattern gaskets always end up blowing and its a false economy, get a proper VW one.