It's pretty simple, as mentioned there are a couple of different oil filters fitted, take the number off the old one, if it's a genuine one it will most likely be one of these:
Ebay is awash with genuine filters, often no more than pattern ones.
The oil filter should spin off with your hand unless someone has screwed it on too tight, then a filter strap or chain might be needed to get it moving, most motorfactors will sell something suitable.
NEVER hammer a screwdriver though one to use as leverage, I've seen plenty chew up just leaving the top ring of the filter stuck in place.
Just warm up the engine for a few minutes (you can warm it through after adding engine flush, but I'm not a lover of the stuff).
Undo the drain plug and let it drain for 10 minutes or so.
Clean off the drain plug and hole, then refit the drain plug, it only needs 15lbs of torque, so don't over tighten it.
Pull the oil filter, make sure the old O ring comes off with it.
Lightly smear clean oil on the new O ring and fit it to the new filter without any kinks.
Now clean off the sealing surface on the engine, a dap of petrol/white spirit on a rag will do, then screw the new filter on hand tight. I usually gauge tightness by screwing it up as tight as I can with one hand.
It takes around 3.5 litres, add around 3 let it settle on the flat for ten minutes, then top up until you get the right level on the dip stick, this saves over filling.
Start it up and check the drain plug and oil filter for leaks.
If you're going to use Eurocarparts, there are discount codes floating around various forums, these tend to work when they haven't already a sale on, but Euro are like DFS, there's always one on!
I borrowed this one from a Corsa site, UKCN25
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