I know the UK doesnt work with US games but does the Wii Fit work with the US console?

I don't think the wii fit board itself has the region lock. I think the wii fit board will be compatible with all system (US, UK, EU, Japan) and the only problem is you gotta have a match system in order to let the game one. For example, you need to have a same version wii fit game and wii console. Like for myself, i had 2 wii system (1 Jap version and 1 mod backup version) and I can use the board on both system without having any problem. However, I do not have the backup version wii fit game otherwise I can let you know on that.