Do German Wii games work on UK Wii consoles?

No they are not. UK Wiis run PAL games only. US Wiis run NTSC games only. Although you can make your Wii region free, which will let it play games from all over the world. You will need to softmod or chipmod your wii to do this. Softmodding is easy to do though (you can check this easy guide out for more info: www.howtomodyourwii.com)