they would both fit, the offset is the distance in mm from the centre of the hub to the outer edge. low offsets will stick out of the arch further, high offsets sit further in.
so an et5 will sit out of the arches, and et50 will touch the suspension. et35 is about right on most golfs so a few mm either side will be fine. both sets will sit further out than your current wheels which will look cool but not rub your arches.
