You may have to get in and clean some of the stuff out, part and parcel of cars man, you're gonna get dirty. I have been 6 shades of filthy just doing a service...on a 16M Grader, lol!
A good solid plasic bristled brush as a parts cleaning brush does come in handy to get some of that grime off, cos some of it will bake on and the kero or degreaser won't sufficiently dissolve it to get it off.
Just make sure though that any degreaser you spray isn't left to sit on plastic or rubber lines for too long, it eats then
mnomnom:
The other thing you may want to do, is if you are running a pod filter, either put a plastic bag over it and zip tie that in place, or remove it and put a plastic bag/bit of rag in its place temporarily. Degreaser will strip the protective oil off your pod, so it won't work anywhere near as well, plus the spraying of water and chemicals around the engine will cover it in gunk. For the sake of a few minutes pulling that off, it'll save you in the long run, from either a) buying a new filter or B) having to clean the shit out of your current one.
I mean, if this leak is something as simple as a slight blowout in the rocker cover or head gaskets, then it's pretty simple to replace (If you are prepared to redo your timeing after taking the head off), and it's not too expensive.You don't even have to take the engine out!! (Well, it's 6 of one, half a dozen of the other really, I do timing in most cars, some people swear by not doing it)
From googling, the head gasket looks like the culprit in this endeavor, any chance of getting a couple of pics of the engine bay once you have cleaned it up, and afterwards once you have given her a run? A good decent run (in my books at least) is where you let her warm up in the driveway, take it for a gentle cruise around town up to say the highway/freeway/motorway and then give it a boot up to road speed, drive it for a while at road speed and then ease it back down until she sits in your driveway for 5 minutes. Then you shut her off, go make a cup of coffee and have a smoke, upon completeion of coffee and smoke break, go back to vehicle and have a look at what the result is.
One other thing, grab the dipstick, check the level. Call me lazy, but I pull out my phone and take a pic of it, and then when I get back, I take a pic of it again and compare the two...Lazy I know, but hey, it's so much easier than marking a piece of paper. Just make sure the state of the engine is exactly the same when you check the oil, so if she had no oil in the top of the motor at the start of the day when you check her first, make sure she has enough time to drain back down into the sump at the end of your run, otherwise you are definatley gonna see oil drop, that is, in reality, not there.
This method has done me pretty well in both my ute and some mates cars that I have had to diagnose, so it's not a big thing to do, you're not smashing the engine hard enough to break it, and you're not doing anything too abusive. Should take around 30-45 minutes to do this, you should lay down anywhere from 40-50km. That's my experience on using this method in the Bega Valley, around Albury Wodonga, and in Darwin NT...so not any major cities, as long as you nurse it up before giving it a good boot, and then nurse it back down, you should go through the full pressure range of the motor.