Most Vauxhalls have a fuse diagram on the fusebox lid.I would think the Holdens would be similar? If you have no lid or handbook,you will need to purchase a manual (commonly by Haynes in UK),these have wiring diagrams and fusebox layouts and ratings etc.
There is no online resources that provides the 2001 Holden Astra CD workshop manual for free. Try contacting Holden for a copy of the original manual.
in the fuse box
It is important to have a diagram when making changes to a car. For 2001 Astra Convertible, a diagram can be found in the maintenance book.
You can find the free wiring diagram for the Holden VY UTE online at places like Only Repair Manuals and Free Book EZ. You can also find the diagram at places like Motore.com.
In the owners log book
there should be a sticker with that diagram on it under your hood somewhere.
This diagram would be available with an image search. You can find some that are labeled and some that are not.
You can find a fuse diagram for a 1982 Chevy S10 in the owner's manual. You can also find it at various auto stores.
If you will crawl under the vehicle and look closely on the engine block you will find the oil filter.
haynes workshop manual or migweb.co.uk
You need to try to get your car to your nearest Holden dealer to be placed onto a Diagnostic machine. It will cost about $99.00 to find out what the problem is. I have a 2001 Holden Astra which has the emission light on at the moment too. The problem you are having is due to a sensor cut out which will cause the engine to cut out.
You can find a diagram of a fuse box for a 1982 Chevy Silverado C10 in the owner's manual. You can also find it at various auto stores.