I've sat the UCAT twice and both times I used medify. There are free resources available like mock papers/questions but Medify is good because its a little harder than the UCAT at times and it tracks what you're good and what you need to focus on so you can tailor your revision that way. Plus there's so many papers and questions to get through, it's really difficult trying to finish them all. If you do manage to get through all of Medify's resources, you've kind off guaranteed yourself a good grade anyways (provided you're getting good averages of course). I really think it's worth paying for Medify