Right, as a whole, the song is pretty easy. I've got most of it down. Through the verses I obviously use my fingers. However, the chorus (heavier part) I would prefer to use a plectrum but there's simply not enough time for me to grab one after the finger picking ends as it's 139bpm and 8th notes so it's quite fast. It's not that I can't play it with my fingers, it's just I'd prefer to have more attack on that bit.
just pick really really fast?

just like to mention i just spent five mins staring at your avatar.
I personally use a thumb pick. They're quite often used in classical/fingerpicking. It's basically just a small pick that loops around your thumb to make bass notes loader when fingerpicking. It also has the advantage that you can use it as a pick that's attached to your thumb so you can swap between fingerpicking and strumming with ease. They do cost a bit more than regular picks though, and be sure to try it on for size, you dont want it too tight or loose