Okay, I'm not going to upload L+2 or LR3 yet(I might later), but I've uploaded Ultimate Challenges 5, 6 and 7. You'll need to redownload the style files for UC6 and UC7, I don't think you need to for UC5 though.
Note that UC6 also requires that you have the style file from Lemming Racers 2 or higher. You can download LR2 on the site as well.