Hmm, you got yourself in a bit of a mess.
I am AD something or other I wasn't paying attention but I'll give your story a go.
I would say forget everything you know. Pick one unknown wire, and check it for continuity as a ground, if it is a factory and it is black then it is a ground. Then get your self a wire connected to the + batt. term. and touch them both to your tongue to test for continuity, now if you are still conscious after this(hopefully you did not have the key in as it was not said to put it in the ignition), first thing you want to do is put the UK wire to ground, no result, place key in ignition to acc. and check again, if nothing then place said wire with the ign. off and key out to the 12v wire you installed from the battery. Do this for both of the unknowns, if you figure out nothing then leave them both disconnected and attempt to start. If no luck, then pull and check all fuses. Welcome to the world of $160 electrical trouble"shooting in the dark". Rinse and Repeat after all fuses are good.