Yep. That's aircon oil. It's dripping off the bottom of the dryer unit. By the looks of it it's the pipework going into the top of the dryer.
As above, get the parts (I got my rad+dryer for half the price of ECP from renparts, but as it's used obviously you aren't guaranteed it'll work but if it doesn't get them to swap it), get de gassed, and do the following.
Jack the front of the car up (you'll need to slide the radiator out)
Pop off the front bumper.
Loosen the 4 bolts holding the radiator in, then the pipes going into the driver's side of the rad (these are retained by bolts too, although I believe they're external torx heads) and into the dryer on the passenger side.
Slide the radiator down and out the bottom (I had to uncabletie the fog light loom too, but it may not be necessary), taking car not to dink the engine radiator behind it.
Smear some AC oil on the seals before fitting them to the new dryer and radiator, then put them on the connections, before sliding the new radiator up and refastening, and re connect the pipework.
Reattach your bumper and toddle off to Kwik Fit.
Get them to put 700 grams in, and tell them to vac it down for an hour.
Done.