okay, I would recommend maybe starting with something a little more basic, like SSM brake van to get practicing with soldering. Even before that practice soldering with some scrap pieces of brass, even the frets from the Maedb kit.
Also, I would recommend getting this book it's old but very good http://www.amazon.com/Etched-Loco-Construction-Iain-Rice/dp/090686786X
I'm using it as I find my feet with building etched kits. I know you're eager to build an 800 kit but I would practice on something a bit more simple first.