Thanks Kindle! 
Just a quick update. First of all, thank you SO much to everyone on this thread, you've all been really helpful and I've found all of your suggestions and advice really useful.
This is going to sound awful, but I've had a massive crisis of confidence and have rethought my decision to apply for this role. I've given it a lot of thought, and have decided unfortunately not to apply for the job. I panicked when filling out some of the application, and felt as confused at some of the questions they were asking as I did a few days ago. When I started the application a few days ago, I thought that I just needed some time to help me come up with suitable answers and good examples that met the criteria.
However, I found that even with the time I've spent thinking about the application over the last few days, I don't feel that my answers (and the experience that I have) fit the competencies.
This is a really frustrating situation, and I really hope that it doesn't come across that I'm ungrateful in any way for all of these help that you've given me on this thread. You've all been absolutely brilliant, and I've been so lucky to have your support.
I've now decided to focus on applying for voluntary roles to give me the skills that I need to then apply for paying roles that I would like to go into (communications roles, so similar to this role).
This feels in a way as if I'm taking a step back, because I really do need a paid job at the moment. I'm working for about an hour a week as a tutor, and have ad-hoc tuition-related jobs that I'm also doing, to pay the bills. However, I do think that relevant voluntary work will be really helpful (and enjoyable!), and it is something that I want to continue with once I find regular paid work again.
If anyone has any advice following this post, I would of course be grateful to hear it :)
Thank you so much again everyone.