Hey Lucy,
Firstly I recommend joining a Facebook group called 'So you want to be a Paramedic?', there is loads of people in the same boat as you, asking similar questions and everyone is really friendly about helping you get into the profession.
I've heard a lot of good about the Access to Paramedicine Via distance learning, as yes, it does give a more specific learning course to a university course in Paramedic science, and it does show you're able to learn on your own accord. If it Paramedicine you want to study and you're confident that you'll be able to keep a consistent workload online, it may be a good choice. However you do raise a good point, if you're on the edge of paramedicine (Or in general want to have a solid backup) Then an Access to HE (Either Healthcare or Science) is a good choice also, you get more involved with the subject and meet new people along the way, they help you with other topics like IT skills and communication which, while they're boring, tend to be really helpful in the long run.
I myself did an Access to HE science diploma (As I prefer science as a whole and biology is very relevant to *most* healthcare subjects.) It was a great experience and I would recommend that route to anyone with a desire into university courses.
Hope you found this somewhat useful, wish you all the best.
Good luck.