Greetings, Liam !
Just go to Arturia's homepage, click on the picture of the Jupiter 8 at the top of the screen, click on the "Try" button, download either the Win or Mac version, install it and enjoy! Alternatively, there is a "Demo version" link in the Jupiter 8V box just below and to the right of the top-screen picture. I'm saving my pennies for this one. Even though the presets for the demo are few, they give a pretty good idea of what this product will do.
Peace,
Dave