I have the Holden version of the Astra, they are all much the same, a Opel designed in Germany, then sent out to the big wide GM world pretty much as the Germans designed them, no significant changes. I also have the 1.8L NA engine.
As GMBoy said above, the have issues with their HT leads / coil packs, I did mine about 1 year ago because it started to run rough. I did the spark plugs at the same time.
Keep on top of the timing belt, every 100,000 miles (or a bit less) from memory.
Fun little cars that handle quite well for what it is.
Hey what oil does your owners manual say to use ?
My Australian OM says 10W-30 or 15W-40 in either A3/B3 or A3/B4, with no mention of API or ILSAC. I'm sure yours says something different even though it's almost the exact same car. OK my steering wheel is on the other side, but apart from that...