Not sure of the location of the fuse you require but if it's in the main fuse box there should be an icon for it moulded into the fusebox cover.
If it's like the early Astras' there are a couple of fuses and relays at the back of the fusebox, you will need to remove a couple of screws to drop the box down to check. Those fuses on the Astra were, if I remember correctly, No 19 and No 20, and I think one was for central locking,but dont quote me on that.
ANON
October 2007