With the LSAT, I'm considering doing a JD so I've researched it a little (although I've never taken it!). The only practise tests worth doing are found for free on the LSAT website. I think there are a lot of US companies out there to scare students into thinking that they need to take a prep course.
Also, I've heard that your LSAT score doesn't have to be *that* high for UoM entry (I'm not really sure what that means though) compared to the required scores of US universities of similar prestige.
They did a review of PhB last year and one of the suggestions that came out of it was that students should have the option of doing PhB/LLB (the most pretentious degree ever!) but it wasn't implemented. Plus, if PhB students were to successfully complete their degree they would probably get into a JD afterwards fairly easily anyway.