Gearbox leak? Core plug issue?
 

I had the under tray off earlier and I’ve noticed an oil leak coming from around the transmission mount area. Can anyone help shine a light on if there is a hole in the transmission housing causing a leak or is this supposed to be a void?

fluid colour is the clue...
 

Hi there.. the area circled seems to be the joint between engine & gearbox, my suspicion would be the clutch slave cyl (assuming its a manual) is starting to leak some (brake) fluid.. if its clear/yellowish, then would be the case, if engine oil (dark & black) not the slave.. what sort of miles has yours got on it ?

Also take a look at the brake reservoir level, (the clutch shares one half of this), and if your seeing it dropping or needing top up, probably confirms the slave cyl could be the problem,, they are often the part that goes before the clutch wears out,,