Holy Moley dude! Well I'll tell you what I used anyway, and how I went about it. I'd personally get myself some decent degreasers first of all. Autosmart G101 (get some spray bottles too, dilute it 1:2, 1:6 or 1:10 for lighter stuff. You'll even have to use it neat at times! Rubber gloves! Dries up your hands!), GUNK degreaser (which stinks!), or Chemguys bare bones?
You'll then need an array of different brushes, moderately stiff, not too stiff, just something to agitate the waxoyl / dirt, a little stiffer than a toothbrush though. Take care on the paintwork inside the bay!

For the overall rubbish / debris and grime, I started off with a pressure washers, around the legs and bulkhead. I'd stay away from the distributor and electronics personally though (as I've found out a few times in the past!

)
Work systematically, (don't underestimate the amount of time it takes with some sections, as it can take bl**dy ages!) section at a time, from top to further down. Lower parts being the lower parts of the legs / following into the front arches and the cylinder head etc.
Finally, before starting a section, remove the water bottles, battery if you want, airbox / headlight cowling, and cover anything more vulnerable with clingflim. Then - GET SCRUBBING! Let me know how you get on! (There's a LOT of waxoyl around these bays lol!) Good luck
