Thanks for the input everyone.
@Longship, when you say "these are the wheels and tyres I fitted mid December", are you referring to penguin17's 16" Autec?
I'm very tempted with these, the spec is right, the only difference is the offset where my Skoda states ET50 and his are 46 and found Autec do these in various offsets.
I doubt the 4mm will result in any issues, plenty of room in the Octavia arches but wanted to be sure I don't end up with a set of wheels in my garage that I have to move on again :-)
If anyone knows a little more that side (ET 50 versus 46 on an 2012 Octavia Estate) that would make me more comfortable to go ahead ......