Hi, I had the same problem but it all turned out to be a lot easier than I thought it would be.
Once the undertray was removed, not easy when you don't have the car up on ramps, the sump drain plug is towards the back of the black steel engine sump cover. You will need an 8mm square plug driver tool to remove it. Remember that you are draining about 7 litres of oil
so a couple of bowls may be needed to catch all of the oil
A copper washer will be needed to reseal the plug.
The filter is inside the black plastic housing that is in front of the engine, just in front of the black sump cover. Unscrew this and the filter comes out with it (remember that more oil
will also drain out from there).
The 'O' ring that seals the black plastic cover into the housing should be replaced (mine came with the filter).
It's all very easy. The most difficult bit was finding a suipplier if the 5W-30 oil
that was compliant with the RN0720 specification.
I hope that this helps.