Hi Liam,
We've written a little help guide on our website for new designers applying for jobs (from a design agency's point of view). It's based on our own experiences with job applicants and things we appreciate (and some we don't!). You can view it here:
Design Job Career Advice | Graphic Design Job Applications | Design Agency Job Advice | BML Creative | BML Creative
Hopefully it might open a few doors, or at the very least stop them from being slammed shut!
Good luck with the hunt.
David