Liam this sounds EXACTLY like what happened to me a few weeks back, I also broke down near an auto store bought plugs and a plug socket
I limped it home (knowing I may be killing the cat).
I suspected a coil pack failure (over fueling causing it to sound like a rally car) but also changed the O2 sensor in the process.
One think I noticed was my 02 sensor wasn't as tight as it should be so I don't know if that had also effected things (and added to the noise).
After replacing both the coil pack and 02 sensor the cars up and running again.
I was lucky that I had both on my spare engine.