I tried to improve matter. I have bought many a car with the belt out a cog or even two, and they all ran all right. There is a tool for the V6 Omega which sets the cams precisely, none for the 4 cylinder or the Astra.
you have the cam locking chocks in the kit , these should have been inserted and the crankshadt locked BEFORE you removed the belt
As per my photos
on the VVT cams the timing marks do NOT line up
rewatch or watch
the video
https://www.youtube.com/watch?v=bolu-wkxYzwIt's IMPORTANT
pay attention at 2 mins 40 seconds shows the marks on the cams, which DON'T line up
so use the cam locking tool wedges and the crankshaft locking bracket
you should not struggle to get the belt back on
IF ,once you timed it correctly with the locking kit ,you still have issues ,then you will need to look into the VVT
sorry for the late reply , not long got back
read DG's post that he just snuck in before i had chance